EVALUATION OF AMBIENT AIR QUALITY OF LAGOS METROPOLIS: CASE STUDIES OF OKOTA AND SURULERE AREA

ADEWALE ODERINDE

Air pollution is one of the major environmental problems confronting developing countries like Nigeria. Lagos, a state in Nigeria is endowed with many commercial and industrial activities. These activities as well as vehicular emissions, use of generators, biomass combustion, refuse burning among others releases a variety of substances into the atmosphere, thus leading to the pollution of the air. Hence, a high degree of air pollution control is essential. In this study, the air quality of Okota and Surulere metropolis of Lagos were assessed and evaluated for pollution and its implications determined. Data for the study was generated through sources like questionnaires, observations, and direct measurement. The air pollution measurements were carried out using direct reading, automatic in-situ gas monitors: KANOMAX Handheld Laser Particle Counter (model 3887A) for particulate matter (PM0.3, PM0.5, and PM5) while TOXIRAE II for CO, SO2, and NO2. In Okota Metropolis, the monitored junctions were Cele Bus Stop, Okota Roundabout Bus Stop, and Ago Palace Bus Stop while Ojuelegba, Itire, and Lawanson bus stops were monitored at Surulere metropolis. The University of Lagos botanical and zoological garden was used as the control. The measured parameters were found to be in the following ranges for average readings. For Okota metropolis: CO (1.3 – 28ppm), SO2 (0 – 9ppm), NO2 (0ppm), PM0.3 (7.4 - 96μg/m3),PM0.5 (7.2 – 94.9μg/m3), and PM5 (9 – 66.9μg/m3) while the readings for Surulere metropolis were: CO (0 – 13ppm), SO2 (0 – 8ppm), NO2 (0ppm), PM0.3 (6.4 – 18.8μg/m3), PM0.5 (5.2 – 96.5μg/m3), and PM5 (11.2 – 84.9μg/m3). Results of this study confirmed that the dwellers or passers-by of Okota and Surulere metropolis were being exposed to high levels of the air pollutants (CO, SO2, PM). This shows that people who spend long hours along roadsides at both study areas were at risk of having respiratory diseases. In conclusion, environmental policies should be reviewed. Extensive public awareness/sensitization, strict enforcement of existing legislations should be enforced to curtail air pollution in Lagos.

EVALUATION OF AMBIENT AIR QUALITY OF LAGOS METROPOLIS: CASE STUDIES OF OKOTA AND SURULERE AREA BY ODERINDE, ADEWALE MICHAEL B.Eng. (UNILORIN) Matric No. 149073044 IN PARTIAL FULFILLMENT FOR THE AWARD OF MASTER OF ENVIRONMENTAL MANAGEMENT, FACULTY OF SCIENCE, UNIVERSITY OF LAGOS. SEPTEMBER, 2016 CERTIFICATION This is to certify that this project was carried out by Oderinde, Adewale Michael ___________________ Prof. K.O. OLAYINKA _______________________ Date (Supervisor) ___________________ Prof. W. OKIEI ______________________ Date (Head of Department) ____________________ External Examiner ______________________ Date DEDICATION This thesis project is dedicated to God Almighty, the Alpha and the Omega, the One who was, who is and who is to come. ACKNOWLEDGEMENT All glory is to God, the creator of the heaven and earth for His love, mercy, and faithfulness towards my life through the course of this project report writing. My sincere and utmost appreciation goes to my family members, most especially my lovely and caring parent, Mr. and Mrs. Emmanuel Olayiwola Oderinde for their moral, academic, financial, and spiritual support given to me from my inception on earth till this present time. I pray that may God Almighty in His infinite mercies cause you to eat the fruit of your labour in peace, good health, and longevity of life (Amen). I sincerely appreciate my Supervisor, Professor. Kehinde Ololade Olayinka for her unrelenting efforts towards this project work. What a jolly good lecturer you are! I acknowledge the positive contribution of Professor Segun Ayejuyo for the way he played his role as our course advisor and Dr. Adetoyin Fatunsin for her immense contribution towards this project. My appreciation also goes to all my classmates, especially Kingsley Nwabugwu, Grace Olohi, Anjolaiya Aderibigbe, James Itopa, Omowanle Oluwadare, Soetan Oluwagbemisola etc. Finally, O God our help in ages past, our hope for years to come. Thank You Jesus. ABSTRACT Air pollution is one of the major environmental problems confronting developing countries like Nigeria. Lagos, a state in Nigeria is endowed with many commercial and industrial activities. These activities as well as vehicular emissions, use of generators, biomass combustion, refuse burning among others releases a variety of substances into the atmosphere, thus leading to the pollution of the air. Hence, a high degree of air pollution control is essential. In this study, the air quality of Okota and Surulere metropolis of Lagos were assessed and evaluated for pollution and its implications determined. Data for the study was generated through sources like questionnaires, observations, and direct measurement. The air pollution measurements were carried out using direct reading, automatic in-situ gas monitors: KANOMAX Handheld Laser Particle Counter (model 3887A) for particulate matter (PM0.3, PM0.5, and PM5) while TOXIRAE II for CO, SO2, and NO2. In Okota Metropolis, the monitored junctions were Cele Bus Stop, Okota Roundabout Bus Stop, and Ago Palace Bus Stop while Ojuelegba, Itire, and Lawanson bus stops were monitored at Surulere metropolis. The University of Lagos botanical and zoological garden was used as the control. The measured parameters were found to be in the following ranges for average readings. For Okota metropolis: CO (1.3 – 28ppm), SO2 (0 – 9ppm), NO2 (0ppm), PM0.3 (7.4 - 96µg/m3), PM0.5 (7.2 – 94.9µg/m3), and PM5 (9 – 66.9µg/m3) while the readings for Surulere metropolis were: CO (0 – 13ppm), SO2 (0 – 8ppm), NO2 (0ppm), PM0.3 (6.4 – 18.8µg/m3), PM0.5 (5.2 – 96.5µg/m3), and PM5 (11.2 – 84.9µg/m3). Results of this study have confirmed that the dwellers or passers-by of Okota and Surulere metropolis were being exposed to high levels of the air pollutants (CO, SO2, PM). This shows that people who spend long hours along roadsides at both study areas were at risk of having respiratory diseases. In conclusion, environmental policies should be reviewed. Extensive public awareness/sensitization, strict enforcement of existing legislations should be enforced to curtail air pollution in Lagos. TABLE OF CONTENTS Title Page i Certification ii Dedication iii Acknowledgement iv Abstract v Table of Contents vi Chapter One Introduction 1.1 Background of the Study 1 1.2 Environment 2 1.3 Air Quality Standards 19 1.4 Statement of the Problem 22 1.5 Significance of the Study 23 1.6 Aim and Objectives of the Study 23 1.7 Scope of the Study 24 Chapter Two Literature Review 2.1 Global Perspectives 25 2.2 National Perspectives 28 Chapter Three Research Methodology 3.1 Description of Study Areas 33 3.2 The Study Approach 34 3.3 Data Collection 35 3.4 Method/Monitoring Design 35 3.5 Limitation of the Methodology 39 Chapter Four Results and Discussion of Findings 4.1 Results 41 4.2 Discussion 73 4.3 Effects of Measured Air Pollutants 74 Chapter Five Conclusion and Recommendations 5.1 Conclusion 77 5.2 Recommendations 78 References 80 Appendix I: Tables of Results Appendix II: Questionnaire CHAPTER ONE INTRODUCTION 1.1 BACKGROUND OF THE STUDY The metropolitan area of Lagos State is the largest and most complex urban area in Nigeria and it contributes significantly to the economy of the nation. It contains the largest manufacturing sector and provides employment for over 45% of the skilled manpower of the country. It also represents 0.4% of the total landmass of the country. The projected population of the city in the year 2017 is 25 million. The rate of population growth has been in excess of 9% per annum, resulting in additional 300,000 per annum or 25,000 per month or 833 persons per day or 34 persons per hour. In terms of population density, whereas the national average is about 100 persons per km, Lagos State approximates 2,400 persons per km and in excess of 15,000 persons per sq. km in some local government areas, namely, Lagos Mainland, Mushin, Oshodi/Isolo and Suru-lere (Taiwo, 2005). Air pollution is one of the major environmental problems confronting Lagos. The operations of industries, as well as other anthropogenically related activities such as biomass combustion, refuse burning and traffic emissions releases a barrage of substances like volatile organics, oxides of carbon, nitrogen, and sulphur, particulate matter, heavy metals and other toxics into the atmosphere at levels that most times exceed both the national and international guidelines (Tawari and Abowei, 2012). At such levels, these substances poses serious potential health hazards. High levels of ambient air ozone can cause serious damage to health. The health hazards include shortness of breath, nausea, eye and throat irritation, and lung damage (Menezes and Shively, 2001). Hence, the need for assessment of the quality of air in Lagos and to proffer lasting solutions. 1.2 ENVIRONMENT The environment has different meanings in different disciplines. In general, the environment is where we live. It is divided into two types: natural environment and built environment. The natural environment encompasses all living and non-living things occurring naturally in the area while the built environment refers to the human-made surroundings that provide the setting for human activity e.g. buildings, parks, cities, and supporting infrastructure such as transport, water supply and energy supply (Dawei, 2012). In broad terms, the environment is made up of four major components. They are the atmosphere (a layer of gases surrounding the Earth), lithosphere (the rigid, mechanically strong, outer layer of the Earth), hydrosphere (all the waters of the Earth - water on, under, and over the surface of the Earth), and the biosphere - global ecological system integrating all living beings and their relationships, including their interaction with the elements of the other parts of the Earth (Dawei, 2012). Therefore, any description of the existing state of an environment must include the characterization of these major components. The atmosphere is one of the four major components of the environment extending up to about 500km above the Earth surface. It consists of a mixture of gases that play important roles in sustaining life on Earth. 1.2.1 AIR Air, an odourless, colourless and essential commodity to all life on earth is all around us. It acts as a gaseous blanket, protecting the earth from dangerous cosmic radiation from outer space. It is actually a combination of gaseous elements that have a remarkable uniformity in terms of their contribution to the totality of life. The constituent elements are primarily nitrogen and oxygen, with a small amount of argon. Below 100km, the three main gaseous elements, which account for about 99.9% of the total atmosphere, are N2, O2 and Ar and they have concentration by volume of 78%, 21%, and 0.93% of respectively (Abdul Raheem and Adekola, 2006). The composition of clean dry air near sea level is given in table 1.1. TABLE 1.1: GASEOUS COMPOSITION OF CLEAN DRY AIR Constituents Major Constituents A Nitrogen Oxygen Water Vapour Minor Constituents B Argon Carbon dioxide Trace Constituents C Neon Helium Methane Krypton Hydrogen Nitrous Oxide Xenon Ozone Carbon monoxide Sulphur dioxide Nitrogen dioxide Ammonia Source: (Mackenzie and Mackenzie, 1995) Chemical Symbol Mole Percent N2 O2 H2O 78.084 20.947 0.1 – 5.0 Ar CO2 0.934 0.0350 Ne He CH4 Kr H2 N20 Xe O3 CO SO2 NO2 NH3 0.001818 0.000524 0.00017 0.000114 0.000053 0.000031 0.0000087 trace to 0.0008 trace to 0.000025 trace to 0.00001 trace to 0.000002 trace to 0.0000003 1.2.2 AIR POLLUTION Air pollution is defined as the contamination of air by the discharge of harmful substances, which can cause health problems including burning eyes and nose, itchy irritated throat and breathing problems (USEPA 1994). Also, It can be defined as the presence in the outdoor or indoor atmosphere of one or more gaseous or particulate contaminants in quantities, characteristics and of duration such as to be injurious to human, plant or animal life or to property, or which unreasonably interferes with the comfortable enjoyment of life and property (Odigure, 1998). Pollution of the environment is one of the most horrible ecological crises the world is subjected today. The environment (air, land or soil and water) was in the past pure, virgin, undistributed, uncontaminated and basically most hospitable for living organisms but the situation is just the reverse today. Presently, the environment has become foul, contaminated, undesirable and therefore, harmful for the health of living organisms, including man (Ukemenam, 2014). Pollution on the whole is caused principally by human activities, though it can also be a natural process. The effects of this can not be overemphasized as we see in living organisms, including man and the ecosystem. Air pollution arises from people‟s economic and domestic activities like modern agriculture which requires agrochemicals. Industrial activities are responsible for wide range of pollution. Thermal power station, burning fossil fuel and moving vehicles emit harmful pollutants like sulphur (IV) oxide, nitrogen (II) oxide and carbon (IV) oxide. Some of these emitted gases have been responsible for acid – rain, global warming and malfunctioning of human/animal‟s haemoglobin. Other causes arise from human activities. Air pollution is basically made up of three components and these are source of pollutants, the transporting medium, which is air and target or receptor which could be man, animal, plant and structural facility. 1.2.3 AIR POLLUTANTS Pollutants are substances that are introduced into the environment in an amount sufficient to cause adverse measurable effects on human beings, animals, plant, vegetation or materials. There are different types of pollutants namely; primary and secondary pollutants. Pollutants are referred to as primary pollutants, if they are directly emitted into the atmosphere from sources and exert the harmful effects in the original form in which they enter the atmosphere e.g. CO, NOx, HCs, SOx, particulate matter among others (Zannetti et al., 2007). On the other hand, secondary pollutants are formed when primary pollutants interact with each other in the atmosphere. Examples include ozone (O3), hydrogen peroxide (H2O2), peroxyacetylnitate (PAN), Nitric acid (HNO3), and peroxybenzoyl nitrate (PBN) (SEPA). Classification of pollutants can also be according to chemical compositions i.e. organic or inorganic pollutants or according to the state of matter i.e. gaseous, liquid (aqueous), or solid (Vasarevicius, 2011). 1.2.3.1 PRIMARY POLLUTANTS: Major primary pollutants produced by human activity include: SULPHUR OXIDES (SOX): The most common sulphur pollutant is sulphur dioxide, a chemical compound with the formula SO2. SO2 is produced by volcanoes and in various industrial processes. Since coal and petroleum often contain sulphur compounds, their combustion generates sulphur dioxide, therefore a typical source of SO2 is the exhaust of vehicles that use leaded automobiles. Further oxidation of SO2, usually in the presence of a catalyst such as NO2, forms H2SO4 and thus acid rain (Anderson, 2005). This is one of the causes for concern over the environmental impact of the use of these fuels as power sources. NITROGEN OXIDES (NOX): The most common NOx is nitrogen dioxide and it is emitted from high temperature combustion. Nitrogen dioxide is a chemical compound with the formula NO2. It is one of the several nitrogen oxides. This reddish-brown toxic gas has a characteristic sharp, biting odour. NO2 is one of the most prominent air pollutants and is introduced into the air mainly through automobile exhaust, gas stoves and heaters, wood-burning stoves, kerosene space heaters (Ukemenam, 2014). CARBON MONOXIDE (CO): It is a colourless, odourless, non-irritating but very poisonous gas. It is a product of incomplete combustion of fuel such as natural gas, coal or wood. Vehicular exhaust is a major source of carbon monoxide (Tawari and Abowei, 2012). CARBON DIOXIDE (CO2): It is a colourless, odourless, non-toxic greenhouse gas. CO2 is released into the atmosphere when carbon-containing fossil fuels such as oil, natural gas, and coal are burned in air (Shakhashiri, 2008). It is associated with ocean acidification, emitted from sources such as combustion, cement production and respiration (Ukemenam, 2014). VOLATILE ORGANIC COMPOUNDS: Volatile organic compounds are important outdoor air pollutants. VOCs are defined as organic compounds which easily evaporate and enter the atmosphere. VOCs may include a wide range of organic air pollutants, from pure hydrocarbons to partially oxidized hydrocarbons to organic compounds containing chlorine, sulphur, or nitrogen (Vasarevicius, 2011). They are often divided into the separate categories of methane (CH4) and non methane volatile organic compounds (NMVOCs). Methane is an extremely efficient greenhouse gas which contributes to enhance global warming. Other hydrocarbon VOCs are also significant greenhouse gases via their role in creating ozone and in prolonging the life of methane in the atmosphere, although the effect varies depending on local air quality. Within the NMVOCs, the aromatic compounds benzene, toluene and xylene are suspected carcinogens and may lead to leukemia through prolonged exposure. 1, 3-butadiene is another dangerous compound which is often associated with industrial uses. PARTICULATE MATTER: Particulates, alternatively referred to as Particulate Matter (PM) or fine particles, are tiny particles of solid or liquid suspended in a gas. In contrast, aerosol refers to particles and the gas together. Sources of particulate matter can be manmade or natural. Some particulates occur naturally, originating from volcanoes, dust storms, forest and grassland fires, living vegetation and sea spray. Human activities, such as the burning of fossil fuels in vehicles, power plants and various industrial processes also generate significant amounts of aerosols. Averaged over the globe, anthropogenic aerosols those made by human activities-currently account for about 10% of the total amount of aerosols in our atmosphere. Increased levels of fine articles in the air are linked to health hazards such as heart disease (Molles, 2005) altered lung function and lung cancer. Persistent free radicals connected to airborne fine particles could cause cardiopulmonary disease (Bronwen, 1999). CHLOROFLUOROCARBONS (CFCS): It is harmful to the ozone layer emitted from products currently banned from use. ODOURS: Such as from garbage, sewage and industrial processes. RADIOACTIVE POLLUTANTS: Produced by nuclear explosions, war explosives and natural processes such as the radioactive decay of radon. AMMONIA (NH3): Ammonia is a very soluble colourless gas with a strong pungent smell that irritates the eyes and the respiratory system. Once emitted, ammonia reacts quickly with other air pollutants to form ammonium sulphate and ammonium bitrate, contributing to the overall particulate matter burden (Von Schmeidemesser et al., 2016). It is emitted from agricultural processes such as fertilizer usage and animal waste. Vehicular exhaust and other processes also add up to its content in the atmosphere (SEPA). Ammonia, either directly or indirectly, is also a building block for the synthesis of many pharmaceuticals, though it can be hazardous when in use widely. 1.2.3.2 SECONDARY POLLUTANTS: Secondary pollutants include SMOG: Smog is a kind of air pollution; the word "smog" is a portmanteau of smoke and fog. Classic smog results from large amounts of coal burning in an area caused by a mixture of smoke and sulphur dioxide. Modern smog does not usually come from coal but from vehicular and industrial emissions that are acted on in the atmosphere by ultraviolet light from the sun to form secondary pollutants that also combine with the primary emissions to form photochemical smog (Tawari and Abowei, 2012). GROUND LEVEL OZONE (O3): Ozone is a secondary air pollutant formed in the atmosphere from a chemical reaction between hydrocarbons and nitrogen oxides in the presence of heat and sunlight (Etzel, 2008). Ozone (O3) is a key constituent of the upper atmosphere - troposphere. It is also an important constituent of certain regions of the stratosphere commonly known as the Ozone layer. Photochemical and chemical reactions involving it drive many of the chemical processes that occur in the atmosphere by day and by night. At abnormally high concentrations brought about by human activities (largely the combustion of fossil fuel), it is a pollutant and a constituent of smog (Ukemenam, 2014). PEROXYACETYL NITRATE (PAN): Peroxyacetyl nitrate is a peroxyacyl nitrate. It is a secondary pollutant present in photochemical smog. It is thermally unstable and decomposes into peroxyethanoyl radicals and nitrogen dioxide gas. It is a lachrymatory substance. It serves as a carrier for oxides of nitrogen (NOx) into rural regions and causes ozone formation in the global troposphere. The formation of PAN on a secondary scale becomes an issue when ethanol is used as an automotive fuel. Acetaldehyde emissions increase, which subsequently react in the atmosphere to form smog. Whereas ethanol policies solve domestic oil supply problems, they drastically exacerbate air quality conditions (wikipedia, 2016). PERSISTENT ORGANIC POLLUTANTS (POPS): These are organic compounds that resist chemical, biological and photolytic degradation. Because of this, they have been observed to persist in the environment, to be capable of long-range transport, bioaccumulation in human and animal tissue, biomagnified in food chains and to have potential significant impacts on human health and the environment (Ritter et al., 1995) 1.2.4 SOURCES OF POLLUTION Basically, in whatever form we choose to say it; pollution could be caused by either natural phenomenon or man-made (anthropogenic) inducement. 1.2.4.1 ANTHROPOGENIC POLLUTION Anthropogenic pollutants are the most toxic and are generally emitted where people live, work, and play. It typically causes the greatest health complications (Udotong et al., 2010). They include: BIOMASS COMBUSTION: This simply means burning organic materials such as firewood, coal, bamboo trunks, and dead leaves. For decades, humans have used these as sources of cooking fuel. Of all these, firewood is the most commonly used feedstock (OMAFRA, 2009). The combustion of firewood releases gaseous pollutants and particulate matter. From literature the gaseous pollutants from cooking emissions are carbon monoxide CO, carbon dioxide CO2, sulphur dioxide SO2, nitrogen dioxide NO2, volatile organic compounds and particulate matter. The particulate matter generated is in the form of carbon black, sooth and fly ash which are major components of smoke and are most often within the 10μm size range (Tawari and Abowei, 2012). Figure 1.1: Cooking fuel emissions from biomass combustion REFUSE BURNING: Refuse disposal is a major environmental problem in Lagos. The refuse is usually from multiple sources including domestic, municipal, agricultural and industrial sources. One of the environmentally unfriendly methods of managing the waste is by open burning either on nearby lands or open dumps within the residential vicinities. The composition of the refuse, age of the dump and intensity of the flame usually determines the nature of the air pollutants. Often times the air within refuse burning sites is inundated with VOCs, Carbon oxides, sulphur oxides, nitrogen oxides,Total Hydrocarbons (THCs), as well as various classes of toxic and hazardous compounds via Polycyclic Aromatic Hydrocarbons (PAHs), dioxins, PCBs (Polychlorinated Biphenyls) and heavy metals such as lead, nickel and mercury. USE OF GASOLINE GENERATOR: There is inadequate electric power supply to households, businesses, and industries. The result is that many households, businesses, and even industries operate small, medium, and large capacity fossil fuel electric power generators for electric power supply whose exhaust is a source of air pollution that releases poisonous carbon monoxide. A recent study conducted in 2010 showed that small household generators in Nigeria operate an average of six (6) hours daily, while average distance of generators away from buildings was 5.6m. These alongside poor ventilation have negatively influenced the quality of indoor air in the households causing air pollution (Stanley et al., 2010). BUSH BURNING: Bush burning is a common phenomenon in Lagos, and some times it might be nearby grasses. The process of bush/grass burning leads to the emission of various types of pollutants. Very often the gas stream is inundated with volatile organics and oxides of carbon (CO), sulphur (SO) and nitrogen (NO) depending on the fuel composition and intensity of the flame. Particulate matter usually within the 10μm size range is also produced in the course of the combustion process (Yahaya, 2016). TRAFFIC EMISSIONS: Over 600 million people globally are exposed to hazardous level of traffic-generated pollutants (United Nation 1998). Human exposure to these air pollutants is believed to have posed severe health problems especially in urban areas where pollution levels are on the increase. Pollution due to traffic constitute up to 90-95% of the ambient CO levels, 8090% of NOx, hydrocarbon and particulate matter in the world, posing a serious threat to human health (Savile 1993). On the global scene, Seneca and Tausig (1994) concluded that transportation is the major culprit of air pollution accounting for over 80% of total air pollutants. In Nigeria much attention is focused on general industrial pollution and pollution from the oil industries, with little attention on the effects of air pollution from mobile transportation sources (Faboya, 1997; Iyoha, 2009). Increased pollution from mobile sources is on the increase with per capita increase in vehicle ownership. The consequence of this is the congestion of most Nigeria city roads and a corresponding increase in the burden of air pollutants and their associated effects. Studies conducted by Akpan and Ndoke, (1999) in Northern Nigeria show higher values of CO2 concentration (1780-1840 ppm) in heavily congested areas in Kaduna and (1160-530 ppm) in Abuja. A study of the impacts of urban road transportation on the ambient air was conducted by Koku and Osuntogun (1999) in three cities in south western Nigeria. At the National level, available data on the total number of vehicles registered in Nigeria shows an increase from 38,000 to 1.6 million between 1950 and 1992 (Enemari, 2001). Data from the Federal Road Safety Commission (FRSC) of Nigeria however, indicates that between 1999 and 2004 about six million vehicles (6,000,000) were registered in Nigeria of which 70% of the registered vehicles were cars and 30% buses and trucks. Figure 1.2: Traffic emissions from busy urban roads INDUSTRIAL EMISSIONS: Lagos being the most industrialized city in Nigeria boasts of industries in the five main industrial sectors that are combustion sources: the petroleum industry, chemical industry, metallurgical industry, construction material industry, and paper and pulp manufacturing. These industries emit various kinds of air pollutants. The pollution from these industries adds to the burden of gaseous and particulate pollutants in the air (Jiming and Guowen, 2011). PIPELINE EXPLOSION: The explosion of pipelines occurs either accidentally or by sabotage. In Lagos, much of the pipeline explosions are a product of the latter and they are usually accompanied most times with fire outbreak. The burning flame and smoke from the oil pipelines releases large concentrations of gaseous substances and particulate matter. The substances in most cases include oxides of Carbon and Nitrogen, Volatile Organic Compounds, Total hydrocarbons, carbon black, soot and some heavy metal residues (Ukemenam, 2014). 1.2.4.2 NATURAL POLLUTION Natural sources include:  Dust from natural sources, usually large areas of land with little or no vegetation.  Methane, emitted by the digestion of food by animals, for example cattle.  Radon gas from radioactive decay within the Earth's crust.  Smoke and carbon monoxide from wildfires.  Volcanic activity, which produce sulfur, chlorine and ash particulates. These and many more are reviewed sources of pollutants into the atmosphere, and they contaminate the air we breathe in. The inhabitants of Lagos are daily exposed to various pollutants in the air as explained earlier. We breathe in oxygen, which is a constituent of the air being polluted by these air pollutants from different sources. This oxygen gets polluted, and so as a result of this, we also take in the polluted oxygen as a form of life. 1.2.5 EFFECTS OF AIR POLLUTANTS Air pollutants are present in concentrations that disturb the dynamic equilibrium in the atmosphere and hereby affect man and his environment. The five major pollutants, which together contribute more than 90% of global air pollution, are carbon monoxide (CO), Nitrogen oxides (NOX), Hydrocarbons (HC), Sulphur oxides (SOX), and particulates. These pollutants are known to affect man and his environment in varied number of ways. They are generally classified into the following effects: 1.2.5.1 EFFECTS ON WEATHER, CLIMATE, AND ATMOSPHERIC PROCESSES In general, air pollution is responsible for two main global problems: contamination of the upper atmosphere and alteration of weather and climate. Pollution affects local weather condition and air pollution causes weather to change on a continental or global basis. The distribution and abundance of particulate matters is responsible for local rainfall patterns and hence there is a significance increase in precipitation in and around cities, and this is due to air pollution. Many gaseous pollutants and fine aerosols reach the upper atmosphere, where they have adverse effects on the penetration and absorption of sunlight. According to modern environmentalists, increasing particulate matter pollution may reduce the amount of sunligjt reaching the Earth surface, thereby lowering solar radiation energy at the Earth‟s surface (Heinsohn and Kabel, 1999; Godish, 2004) 1.2.5.2 EFFECTS ON VEGETATION In terms of the damage to plants caused by air pollution, forests could be damaged and agricultural area recording poor growth and yield. This could be caused by the sulphur dioxide (SO2) and hydrogen fluoride (HF) from stationary sources. Plant damage could also result from mobile sources including automobiles. 1.2.5.3 EFFECTS ON MATERIAL AND CULTURAL PROPERTIES The effects of air pollution is not only on people‟s health and living things such as plants, but also extend to man-made items such as materials like metals and cultural properties. To recognize and investigate the effects of air pollution on materials and cultural properties is to evaluate the economic loss from the air pollution and at the same time improve the safe maintenance of public assets. 1.2.5.4 EFFECTS ON HUMANS’ HEALTH This mainly includes respiratory system diseases such as asthma, bronchitis among others as this is the first target organ attacked by air pollutants. Below are each effects of pollutants on humans‟ health. PARTICULATES: Particulates in the atmosphere are known to cause varying deleterious effects in the environment, although it is important to emphasize that the size and shape of the particulate as well as their chemical nature are more vital in this regard than their number. Particulates include dusts, FeO4, V2O5, CaO, PbCl2, PbBr2, fly ash, aerosols, soot, polycyclic aromatic hydrocarbons (PAHs) etc. PAHs for example are important constituents of several organic particulates, which have been found to be carcinogenic. Fine particulates of less than 3 micron in diameter can penetrate through the nose and the throat causing breathing problems and irritation of the lung capillaries. NITROGEN DIOXIDE: NO2 as it is fondly called is a reddish-brown, pungent and irritating gas to respiratory membranes. The background atmospheric concentration of NO2 is 0.5 – 4 ppb. Exposure to nitrogen dioxide emitted from a variety of outdoor sources even at low concentrations can cause chronic irritation of the respiratory tract, headache, loss of appetite, and corrosion of the teeth. Research has also found that extreme high-dose exposure to NO2 may result in pulmonary edema and diffuse lung injury. Continued exposure to high NO2 levels can contribute to the development of acute or chronic bronchitis. The relatively low water solubility of NO2 results in minimal mucous membrane irritation of the upper airway. The principal site of toxicity is the lower respiratory tract. Recent studies indicate that low level of NO2 exposure may cause increased bronchial reactivity in some asthmatics, decreased lung function in patients with chronic obstructive pulmonary disease, and an increased risk of respiratory infections, especially in young children. Nitrogen dioxide is an oxidant gas, which at high concentrations causes lung injury. It reduces the efficacy of lung defense mechanisms against infection (Samet et al., 2000). SULPHUR DIOXIDE: Sulphur dioxide is a colourless but pungent gas that can be tested at 0.3 – 1.0 ppm. When human beings inhale sulphur dioxide in sufficient concentrations, there is a noticeable increase in the breathing rate. The breathing becomes less deep and a general feeling of air starvation is experienced. It acts mainly as irritants, affecting the mucosa of the eyes, nose, throat, and respiratory tract. Acute SO2 related bronchial constriction may also occur in people with asthma or as a hypersensitivity reaction. The high water solubility of SO 2 causes it to be extremely irritating to the eyes and upper respiratory tract. Concentrations above 6ppm produce mucous membrane irritation. Epidemiologic studies indicate that chronic exposure to SO2 is associated with increased respiratory symptoms and reduced pulmonary function (Lipsett, 1992). Clinical studies revealed that some asthmatics respond to as low as 0.4 ppm of SO2 with symptoms of bronchoconstriction (USEPA, 1993). Atmospheric SO2 is transformed ultimately to the anion sulphate (SO42-). The rate of oxidation of SO2 ranges from <1% to 5% per hour during the day, and it is influenced by the intensity of sunlight, humidity and by the presence of nitrogen oxides, hydrocarbons, strong oxidants and catalytic metal-containing particulates (Anlauf et al, 1982). Because of its moderately long residence time (about 4 days), most SO2 is transported a long distance from its point of emission before it is iodized or deposited to the surface of the landscape. Sulphur dioxide which oxidizes to sulphur trioxide may dissolve in body fluids to form sulphuric acid, a corrosive acid. Oxides of nitrogen and sulphur are oxidized to H2SO4 and HNO3 by various photochemical and catalytic chemical reactions that are eventually washed down by rain as acid rain. The acids dissolve in water vapour and ionize into H+, SO42- and NO3- (Odiete, 1999). This acid rain has been reported to cause extensive damage to building and structural materials as well as valuable ancient sculptures. The acidification of soils and aquatic systems have also been reported to alter species composition among plankton, decline in productivity of fish and amphibians and the mobilization of metals, which were initially locked unto sediment/soil particles. Acidification of drinking water reservoirs and concurrent increases in heavy metal concentrations may exceed public health limits and cause injurious effects. Apart from the formation of acid rain, the release of excessive concentration of hydrocarbon into the atmosphere from anthropogenic sources may also result in the hydrocarbon being oxidized in the atmosphere by a series of chemical and photochemical reactions resulting in the formation of various end-products such as carbon monoxide and solid organic and aldehydes. These products from photochemical smog, which is characterized by reduced visibility, eye irritation, damage to vegetation, and accelerated cracking of rubber products. CARBON MONOXIDE: Carbon monoxide is one of the most important pollutants emitted from petrol-powered engines and combustion appliances. When carbon monoxide is inhaled, carboxyhaemoglobin (COHb) is formed through the combination of haemoglobin and carbon monoxide, and when about half of the haemoglobin of the blood is used up, death ensues, as the carboxyhaemoglobin is useless for respiratory purposes. CO is an insidious poison since there may be no warning until a sudden weakness overcomes the victim, rendering him incapable of escaping. Persons poisoned by carbon monoxide exhibit a characteristic bright pink colour of the flesh due to carboxyhaemoglobin (Palmer, 1974). The elderly, the foetus, and persons with cardiovascular and pulmonary diseases are particularly sensitive to elevated carbon monoxide levels. Tissues with the highest oxygen needs such as myocardium, brain, and exercising muscle are the first to be affected. Symptoms may mimic influenza and include fatigue, headache, dizziness, nausea and vomiting, cognitive impairment, and tachycardia. TABLE 1.2: CARBOXYHAEMOGLOBIN LEVELS AND RELATED HEALTH EFFECTS % COHb in Effects Associated with this COHb level blood 80 Death 60 Loss of consciousness; death in prolonged exposure 40 Confusion; collapse on exercise 30 Headache; fatigue; impaired judgement 7-20 Statistically significant decreased maximal oxygen consumption during strenuous exercise in healthy young men 5-17 Statistically significant reduction of visual perception, manual dexterity, ability to learn, or performance in complex sensor motor tasks (such as driving) Below 5 No statistically significant vigilance reduction after exposure to CO 2.9-4.5 Statistically significant decreased exercise capacity (i.e., shortened duration of exercise before onset of pain) in patients with angina pectoris and increased duration of angina attacks 2.3-4.3 Statistically significant decreased (about 3-7%) work time to exhaustion in axercising healthy men Source: U.S. EPA (1979 and 1985) 1.3 AIR QUALITY STANDARDS The concentration of a pollutant in air may be defined in terms of the proportion of the total volume that it accounted for. Concentrations of pollutant gases in the atmosphere are usually measured in parts per million by volume (ppmv) or parts per billion by volume (ppbv). Pollutant concentrations can also be measured by the weight of pollutant within a standard volume of air, for example, microgrammes per cubic metre (µg m-3) or milligrammes per cubic metre (mg m-3), particularly used for particulate pollutants. The amount of pollutants not to be exceeded in the discharge from a pollution source is known as the emission standard or emission limit value (ELV). Air quality has traditionally been controlled by legislation to limit the discharge of pollutants into the environment. The assumption is made that controlling releases achieves a benefit in terms of controlling levels of environmental (ambient) pollution. Air quality standards for air pollution are concentrations over a given time priod that are considered to be acceptable in the light of what is scientifically known about the effects of each pollutant on health and on the environment. Air quality standards prescribe the concentrations of air pollutants that cannot legally be exceeded during a given time period in a specific location. They can also be used as a benchmark against which air pollution can be measured. An exceedence of a standard is a period of time (which is defined in each standard) where the concentration is higher than that set down by the standard. In order to make useful comparison between pollutants, for which the standards may be expressed in terms of different averaging times, the number of days on which the exceedence has been recorded is often reported. In Nigeria, the Federal Environmental Protection Agency (FEPA) now Federal Ministry of Environment is saddled by decree 58 of 1998 to establish environmental guidelines and standards fo the abatement and control of all forms of pollution (FEPA, 1998) while National Environmental Standards and Regulations Enforcement Agency (NESREA) is charged with enforcing compliance with laws, guidelines, policies and standards on environmental matters such as environmental health and sanitation, water quality, noise level, air quality e.t.c (NESREA Act, 2007). As part of the environmental control processes of the nation‟s vast resources, Interim Guidelines and Standards for industrial effluent, gaseous emissions, and noise limitation were published by the nation‟s statutory body (FEPA, 1991). At the state levels, the states Environmental Protection Agencies are saddled with maintaining environmental quality in their respective domains. They are empowered to declare air pollution control areas and to prohibit the use of any fuel/burning of any material, which is likely to cause air pollution in any air pollution control area. In Lagos state for instance, we have Lagos State Environmental Protection Agency (LASEPA). States EPAs are empowered to obtain information relating to pollution in general, to inspect the concerned premises, and to take samples of emissions from sources for analysis. Each state EPA is expected to   Close, prohibit or regulate any industry‟s operation or process. Grant consent within four months after receiving an application and if the application is rejected, allow the industry to appeal to the appelate authority for grant of consent. TABLE 1.3: NIGERIAN AND INTERNATIONAL AMBIENT AIR QUALITY STANDARDS Contaminant Concentrations (ppm) FMEnv (FEPA, 1991) World Bank (1999) CO 10 - NO2 0.04 – 0.06 0.08 NH3 0.28 - SO2 0.1 - O3 0.1 - H2S 0.008 - VOCs 1.9 - PM2.5 - 25µg m-3 PM10 - 80µg m-3 TSP 250µg m-3 80µg m-3 Source: Federal Ministry of Environment, 1991 and WHO ambient air quality guidelines, 2002. ***Concentration is in ppm except where otherwise stated. 1.4 STATEMENT OF THE PROBLEM The growing rate of urbanization is directly proportional to the growing rate of air pollution but not proportional to a comprehensive, strategic plan and technological advancement in place with which the air around us would be protected to avoid its continuous degradation. Since Lagos is an industrialized city, majority of these pollutants come from automotive engines and industries. In comparison with the large volume and varieties of studies carried out in the developed world, exposure studies carried out in Nigeria are relatively scarce (Okunola et al., 2012). Vehicular growth has not been checked properly by environmental regulating authorities leading to increased levels of pollution (Han and Naeher, 2006). Roadside vendors generally spend 8-10 hours on the margins of the road and are continuously exposed to the vehicular emissions as well as fugitive dust (Mani et al., 2013). Many market places, shops, business centres are in close proximity to roadsides thereby exposing these people to harmful pollutants which may have no serious effects now but in the long term could lead to respiratory diseases and possibly death. Hence, the need for the assessment of the quality of air in Lagos and to also help in proferring lasting solutions to this global environmental issue. . 1.5 SIGNIFICANCE OF THE STUDY Here is a research into the present state of the quality of air for the selected areas of study and its likely effects and management which will provide information and database which will in turn help in the control, reduction, and amelioration of the problem arising from degraded air quality, thereby making the environment more conducive for inhabitation. The results of this study will be of awesome benefit as it will act as a guide in academics, policy formulation, and also aid the regulatory bodies in planning to ensure compliance with the bye-laws, codes of practices and recommendations which are in conformity with the appropriate air quality management. 1.6 AIM AND OBJECTIVES OF THE STUDY Since air plays such a vital role in life on earth, good quality air is a precious resource. Air quality is as important as air quantity. The quality of air we take in affects our body systems, hence a need for this study. This study is aimed at evaluating the level of air pollution of the study areas and proffer solutions. The objectives of this study were to: i. Conduct air sampling for gaseous pollutants (CO, SO2, and NO2) and particulate matter at the two study areas. ii. Determine the existing state of the ambient air quality of Okota and Surulere study areas. iii. Determine the difference between the air quality of these selected areas and regulatory standards if any. iv. To provide information about factors responsible for pollution and determine the effects of the air pollutants that are likely to arise from the study areas. v. Suggest mitigation measures to ensure avoidance or lower generation of air pollutants. vi. To improve the quality of data for possible future studies as it will provide regulatory agencies with the scientific data that will enable them to manage and update the national ambient air quality standards. 1.7 SCOPE OF THE STUDY This project will cover three bus stops for each study area (Okota and Surulere). These areas were selected considering their population sizes and activities that occur within them. Administration of a simple and objective questionnaire to the inhabitants will be considered. The results of the administered questionnaires from the six bus stops will be pooled. The information obtained will be subjected to simple descriptive analysis whose outcomes are summarized in the results. Hence, information gathered will be used to analyse the profile of the management programme to be adopted. CHAPTER TWO LITERATURE REVIEW 2.1 Global Perspectives Coogan et al (2011) carried out a study titled „Air Pollution and Incidence of Hypertension and Diabetes Mellitus in Black Women Living in Los Angeles‟. The ambient air quality survey was done with respect to particulate matter (PM2.5) and nitrogen oxides. They made use of COx proportional hazards models to assess incidence rate ratios (IRRs) and 95% confidence intervals (CIs) for incident hypertension and diabetes mellitus associated with exposure to the measured pollutants. The parameters‟ levels were monitored at the residential addresses of the respondents with land use regression models (nitrogen oxides) and interpolation from monitoring station measurements (PM2.5). When pollutants were analyzed separately, the IRR for hypertension for a 10- µg/m3 increase in PM2.5 was 1.48 (95% CI, 0.95–2.31), and the IRR for the interquartile range (12.4 parts per billion) of nitrogen oxides was 1.14(95% CI, 1.03–1.25). The corresponding IRRs for diabetes mellitus were 1.63 (95% CI, 0.78 –3.44) and 1.25 (95% CI, 1.07–1.46). When both pollutants were included in the same model, the IRRs for PM2.5 were attenuated and the IRRs for nitrogen oxides were essentially unchanged for both outcomes. Their results suggest that exposure to air pollutants, especially traffic-related pollutants, may increase the risk of type 2 diabetes mellitus and possibly of hypertension. International Gas Union (2015) presented a paper titled „Case Studies in improving urban air quality‟. The study was aimed at improving the quality of urban air through reviews of four cities that has tackled air pollution in the past. The findings from this study can provide lessons for other cities seeking to reduce the severe health implications of urban air pollution. One of the reviewed cities Instabul experienced worsening air quality because of their population growth and increasing use of coal for domestic heating. The coal being used was primarily a Turkish lignite coal that was relatively low quality and high in sulphur. The coal used contributed to the high levels of SO2 experienced in Istanbul. The annual mean SO2 concentration in Istanbul was measured to be above 220μg/m3. This concentration is approximately 11 times higher than the current WHO guidelines for 24-hour concentration. Istanbul‟s primary strategy in addressing its air pollution problem was to provide an alternative residential heating fuel. The city formed a gas distribution company, IGDAS, that began installing the necessary infrastructure to distribute gas to Istanbul residents. Although Turkey has no significant domestic natural gas production, Istanbul and other cities in Turkey were able to take advantage of Turkey‟s growing role as an energy hub at that time, as several major pipelines from Central Asia, Russia, the Caucuses, and Iran began transmission through the country to supply part of Europe‟s gas. As a result of these changes, Istanbul‟s air quality has improved dramatically. Particulate matter reduced from over 100µg/m3 to just above 50. SO2 concentrations also began an immediate decline. SO2 had fallen nearly 90%, but the annual average concentration remained above the WHO standard daily average of 10μg/m3. The concentrations have continued to decline and were approximately 5μg/m3 in 2011 and 2012. Concentrations of other pollutants such as NO2 and Ozone remain elevated because of the increase in traffic in Istanbul over the past twenty years. But the concentrations of these pollutants are lower than they would have been had Istanbul not engaged in the aggressive measures to promote fuel switching. The experience in Istanbul shows how long-term planning is essential to deploy the necessary infrastructure to support emissions reduction strategies. In recent two decades, several studies have been carried out in Cairo, Egypt. These studies include both anthropogenic and natural contributions to air quality in Cairo. Zakey & Omran (1997) showed that the dust and sand storms occur frequently in spring and autumn while hot desert cyclones known as the “Khamasin” depressions pass over the desert during spring months. They came to a conclusion that the levels of PM in Cairo is increased due to the dust and sand particulates carried by the hot and dry winds into the city. Abu-Allaban et al (2007) made use of chemical mass balance receptor modeling order to examine the sources of PM10 and PM2.5 in Cairo‟s ambient atmosphere. They found that main sources of PM10 included geological material, mobile source emissions, and open burning. PM2.5 was majorly contributed by mobile source emissions, open burning, and secondary species. Favez et al (2008) examined the seasonality of major aerosol species and their transformations in Cairo. Mahmoud et al (2008) investigated the origins of black carbon concentration peaks in Cairo atmosphere. Seasonal and spatial variation of particulate matters was examined in Cairo by Zakey et al (2008). They indicated that the highest concentration of PM10 values was found in industrial and heavy traffic locations. The annual mean PM2.5 and PM10 are observed to be 85 and 175μg/m3 respectively due to the traffic emissions and burning of waste materials. Recently, Safar & Labip (2010) investigated health risk assessments of PM and lead in Cairo. They showed the arid climate is responsible for the persistent high background PM level in this area. This is one of the reasons of the high daily PM10 levels that are above the air quality limits in the country. From the meteorological conditions view, Cairo has very poor dispersion characteristics. Irregular settlements, layout of tall buildings and narrow streets create a bowl effect in the city environment. The high levels of lead were recorded in the major Egyptian cities. Safar & Labip (2010) explained that the concentrations of lead in Cairo are among the highest in the world. They found out that Shoubra Kheima industrialized region has the highest annual average concentration and this was due to the lead smelters in this area during the period of 1998 through 2007. The highest annual average Pb levels recorded were 26.2 and 25.4μg/m3 at the Shoubra Kheima and El Sahel monitoring stations, respectively, during the baseline year (October 98 to September 99). The annual average Pb levels have been gradually decreased when the lead smelters in the area were closed and moved to the industrial area of Abou Zaabal. CCS (2010) report indicated that lead was completely phased out from petrol distributed in Cairo, Alexandria and most of the cities of Lower Egypt in late 1997, and consequently, lead concentration in the atmosphere of Cairo city centre and residential areas gradually decreased. Surface ozone levels were also examined in Cairo. 2.2 National Perspectives A study by Dr. Bola Osuntogun (1999) of the Department of Chemistry, University of Lagos, Akoka on the quality of air of some selected locations in Lagos state made use of two approaches: in-situ measurements and chemical method. Three selected dumpsites (Olusosun, Oke-Odo, and Solus), three industrial estates (Creek Road at Apapa, along Oba Akran Avenue Ikeja, and Eric Moore near Nigerian Breweries), and six heavy traffic stations (Yaba, Ojuelegba, Mile 2, Oshodi, Obalende, and CMS bus stops) were used as the locations over a period of about 10 months within the Lagos metropolis. The following results were obtained during the study. The in-situ results obtained using both 412 multi-gas monitors and Testo 350 Flue Gas Analyser during the period of study (June 1998 to April 1999) showed the carbon monoxide concentration was higher in one location of Oke-odo (13 ppm) than at Olusosun (12 ppm) and Solus (9 ppm). The NOx and SO2 concentration were found to be similar in the three dumpsites. At the Industrial Estate in Apapa, the CO concentration was found to vary from 9 to 85 ppm, which was higher than that at Eric Moore, which varied from 18.5 to 40 ppm. The NOx and SO2 at both locations were almost the same. The CO concentrations were found to decrease in the order, Oju-elegba, Oshodi, Mile 2 and lastly at Yaba. The average concentrations of carbon-monoxide in heavy traffic stations was 49.32 ppm, while at industrial estates – 36.75 ppm and at the dumpsites 10.76 ppm. SO2 average concentrations were 0.166 ppm at the traffic stations, and 0.670 ppm levels were detected at both industrial and dumpsites. The NOx concentrations were 0.220 ppm at the dumpsites and 0.333 ppm at both industrial and traffic stations. The chemical method results show that concentration of SOx was highest at Olusosun followed by Oke-odo and at least at the Solus location. The NOx concentration was also in the same order. The SO2 concentration was higher at Ikeja than at Apapa. But the concentrations of NOx were similar in both locations. The SO2 concentration in heavy traffic stations was highest at Oshodi, followed by Obalende, then CMS and negligible at Yaba bus stop. The NOx concentration was highest at Obalende, followed by Yaba, then at CMS and at least at Oshodi. The average concentrations for SO2 at Dumpsites were 0.555 ppm, Industrial estate 0.515 ppm and Traffic situations 0.097 ppm. Average concentrations for N0x were Dumpsites 0.190 ppm, industrial estate 0.225 ppm and traffic stations 0.113 ppm. Comparing the results of both methods, it can be noticed that the in-situ methods give slightly higher concentrations for sulphur dioxide and nitrogen oxides. The values obtained by either of the methods were all higher than the Nigerian national standards (FEPA standards) for ambient air, which are as follows: C0 – 10 ppm, SO2 – 0.01 ppm and N0x – 0.04-06 ppm. Jaji (2003) carried out a study on vehicular emission in Kosofe, Ikeja and Mainland Local Government areas during the rush hour period. The following results were gathered: the average results for CO2 in the areas monitored were Ketu (1.22 ppm), Ojota (1.24 ppm), Ikeja GRA (2.24 ppm), Alausa (1.99 ppm), Yaba (0.91 ppm), Oyingbo (0.93 ppm), Mile 2 (1.31 ppm) and Ikeja under bridge (1.15 ppm). The CO emission at Ketu was (12.25 ppm), Ojota (19.00 ppm), Ikeja GRA (2.00 ppm), Alausa (1.50 ppm), Ikeja under bridge (15.50 ppm) while NO2 at Ketu was (1.75 ppm), Ojota (0.50 ppm), Ikeja (0.25 ppm), Alausa (0.50 ppm), Yaba (0.67 ppm), Oyingbo (1.00 ppm), Mile 2 (1.22 ppm), Ikeja under bridge (1.00 ppm). It was observed that the concentration of CO was highest at Ikeja and lowest at Yaba (0.91 ppm) while NO2 was highest at Ketu (1.75 ppm) and lowest at Ikeja GRA (0.25 ppm). Jaji reported that the high CO at Ojota could be linked to traffic congestion that is always on a high note there and the high level of CO2 could be attributed to the presence of industries in Ikeja. Using these datas, the author of this study concluded that Lagosians should watch where and where not to be within the city and at particular times of the day for reasons no other than health implications of some of the vehicular emission emitted into the atmosphere. Zagha and Nwaogazie (2014) carried out a study titled „Roadside Air Pollution Assessment in Port-Harcourt, Nigeria‟ between the 8th and 13th of September 2014. In this study, the level of air pollution along roadsides at selected locations in Port-Harcourt metropolis was assessed. Carbon monoxide, Sulphur dioxide, Oxides of nitrogen and Particulate matter (PM10) were monitored in the study area at four locations which were three junctions (Mile One Junction, Rumuola Junction and Artillery Junction) along the Port-Harcourt/Aba Expressway and Bodo street in the new GRA was used as the control. The air pollution measurements were carried out using direct reading, automatic in-situ gas monitors; HAZDUST Particulate Air Monitoring Equipment for PM10, VRAE Multi Gas Monitor for SOx and NOx and AEROQUAL Gas Detector for CO. Sampling was carried out for six consecutive days; three days for each location. All sampling locations were sampled at different times of the day (morning, afternoon, and evening). Morning readings were taken between 8am-11am, afternoon readings between 12pm3pm and evening readings were taken between 4pm-7pm. All measured pollutants were within permissible limits at Bodo Street in the New GRA. This could be attributed to the low traffic density in the area and also the presence of trees and shrubs planted along the street which serve as carbon sink. The concentrations of carbon monoxide in the study area are varied between a minimum of 060.24ppm. The maximum value was observed at Rumuola junction and it exceeds prescribed hourly standards by the United States Environmental Protection Agency (USEPA} and Department of Petroleum Resources (DPR) Nigerian standards which are 35ppm and 0.26ppm, respectively. This could be as a result of the high traffic density at this location, absence of trees planted along roadsides and the very slow movement of vehicles (traffic congestion). Highest sulphur dioxide concentration was also observed at Rumuola junction at 0.75ppm exceeding USEPA hourly standard of 0.075ppm, however within the limit set by the DPR at 1.34ppm. Also, particulate matter was within the limits set by the DPR at all locations between 150 and 230 µg/m3. Although most values looked relatively low or within limits at the sampling locations, when converted to air quality index, it was observed that all locations with the exception of Bodo Street in New GRA, posed serious health risks to individuals who spent long hours at these locations. Results of this study have confirmed that the dwellers or passers-by along the Rumuola, Artillery and Mile One Junctions were being exposed to high levels of the air pollutants (NO2, SO2, CO and SPM). Persons at the Bodo Street in New GRA, away from high traffic density, were safer and enjoy a much healthier environment. Abdulkareem (2003) carried out a research on „Urban Air Pollution Evaluation by Computer Simulation: A case study of petroleum refining company Nigeria‟. Air samples were collected to determine the extent of pollution by the release of the gas flare by the petroleum refinery industry in regarding to pollutants such as NO, CO, SO2 and total hydrocarbon. In this research, air samples were collected at various distances of 20m, 40m, 60m, 80m and 100m away from the flare stack to determine the concentration of pollutants in a flared gas in the months of June and July. The result of the simulation of model developed from the modified principle of gaseous dispersion by Gaussian showed a good agreement with the experimental results with average correction coefficient of 0.99. It could be observed that the experimental results shows that there is an appreciable variation in the concentration of pollutants at the various distances of 20, 40, 60, 80 and 100 m away from the point of discharge. It could be seen from the results that the concentration of pollutants varies with the thermal efficiency. The higher the thermal efficiency the higher the concentration of the pollutant dispersed and vice versa. This could be attributed to the fact that the thermal efficiency is inversely proportional to the stack efficiency. The results also revealed that the concentration of the pollutants at distances of 20,40and 60m from the point of flare does not conform to the Federal Environmental Protection Agency (FEPA) set limit. CHAPTER THREE RESEARCH METHODOLOGY 3.1 DESCRIPTION OF STUDY AREAS Okota of coordinates 6.5174ºN,3.3188ºE is a city under Oshodi-Isolo Local Government Area. It is located on the North-East of Lagos State which itself is situated in the south western part of the country. The Local Government Area is part of the Ikeja Division of Lagos State. At the 2006 census, the Local Government Area had a population of 621,509 people, and an area of 45 km2. Average temperatures are typically between 27ºC - 29.15ºC. Rapidly paced expansion brought about demands for habitable lands in Lagos State from the 1980s. This led to paced population growth of the entire community as construction of residential homes bloomed and small businesses soared (www.isololcda.com). Surulere of coordinates 6.4980ºN,3.3439ºE is a residential and commercial Local Government Area located on the mainland of Lagos. It has an area of 23 km2. At the last census in the year 2006, there were 503,975 inhabitants, with a population density of 21,864 inhabitants per square kilometer. Average temperatures are between 27ºC - 29ºC. It has a humidity of 74%. Surulere houses popular places like Ojuelegba, Lawanson, Costain etc. Ojuelegba which is one of these places is known for its crowded setting and regarded as one of the busiest places in Lagos. It is one of the key transport nodes of Lagos, connecting the city‟s mainlands with Lagos Island and Victoria Island (wikipedia, 2016). Indiscriminate dumping and open air burning of refuse, badly maintained automobiles that run on diesel and leaded fuel, emissions from heavily loaded transportation vehicles and generators are just some of the causes of air pollution associated with these two cities. The climate is tropical with two distinct seasons: wet and dry. Unsteady power supply accounts for the use of small-scale petrol powered generators and lamps. The means of transportation in these cities are majorly cars, motorcycles, and tricycles. Table 3.1: Coordinates of Sampling Locations Sampling Locations Latitude Longitude Sea Level Cele Bus Stop 6.539604 3.284376 15m Okota Roundabout Bus Stop Ago Junction Bus Stop Ojuelegba Bus Stop Lawanson Bus Stop Itire Road 6.516563 3.319395 10m 6.515844 3.319427 10m 6.511604 3.363265 9m 6.512494 3.348588 10m 6.512640 3.349304 10m 3.2 Global Positioning System (GPS) Coordinates 6º 32 22.5744 N 3º 17 3.7536 E 6º 30 59.6268 N 3º 19 9.822 E 6º 30 3º 19 6º 30 3º 21 6º 30 3º 20 6º 30 3º 20 57.0384 N 9.9372 E 41.7744 N 47.754 E 44.9784 N 54.9168 E 45.504 N 57.4944 E THE STUDY APPROACH The method of research involved the collection of data through the use of experimental research, questionnaires, and observations. 3.2.1 EXPERIMENTAL RESEARCH: This involved taking the measurement of considered air pollutants (air quality parameters) using air samplers. This would be discussed later. 3.2.2 QUESTIONNAIRE: This involved the collection of data through the distribution of questionnaires to the inhabitants of the study areas. A total of one hundred and twenty (120) questionnaires spread equally within the two study areas were sampled. The background data of the respondents was the first section and the responses as regards their perception on the effects of air quality on their health was collected. Based on the data collected from the questionnaires, evaluation of the possible effects of air pollution was carried out to determine the problems associated with the emergency trends underlying air pollution within the study areas. In each of the selected areas, random and purposeful sampling method was used to select eligible respondents from respondents. To be eligible, respondents must be eighteen (18) years and above. 3.3 DATA COLLECTION Sampling was carried out for both dry and rainy seasons. The dry season sampling was carried out on the 21st of May 2016 while the rainy season sampling was done on the 9th of July 2016. All sampling locations were sampled twice (traffic peak and offpeak periods) for both dry and rainy seasons. The peak period readings were taken between 7am – 9am and 5pm – 7pm respectively while the offpeak period readings were taken between 10:30am – 11:30am and 9pm – 10pm respectively. Sampling involved open air sampling on the pavements in closest proximity to the roads and at a height of 1m. Measurements were taken after allowing the equipments to stabilise for at least ten (10) minutes before readings were taken in order to provide real time reading of parameters of interest. 3.4 METHOD/MONITORING DESIGN The method employed in this study is in line with world‟s standard using precision equipments in carrying out the measurements of the pollutants. 3.4.1 DESCRIPTION OF AIR SAMPLERS Air quality (gaseous emissions) parameters considered in this study included Carbon Monoxide, Sulphur Dioxide, Nitrogen Dioxide, and Particulate Matter. Air quality measurements were taken using an handheld laser particle counter (model 3887A) for particulate matter while the gaseous pollutants were monitored using ToxiRAE II devices. The handheld laser particle counter (model 3887A) is manufactured by Kanomax USA Incorporation. Its channel sizes are 0.3, 0.5, and 5.0 µm respectively. It has a flow rate of 0.1 cf/min (2.83L/min). It samples for a duration of ten seconds to ninety nine minutes fifty nine seconds (1sec increments). It use a laser diode as the source of light. This particle counter has six different mode of measurements (single, repeat, continuous, calculation, remote, and ISO mode). It has a capacity to store up to 10,000 samples collected. It uses four pieces of AA battery for power source. It is applicable in hospital surgical room, filter testing, IAQ investigation etc. Fig 3.2 Laser Particle Counter (model 3887A) ToxiRAE II (PGM-1100 series) is a full-featured personal clip-on gas monitor that provides a continuous digital display of the selected toxic gas concentration, short term exposure limit (STEL), time weighted average (TWA), and peak values for over ten (10) toxic gases and oxygen deficiency or enrichment hazards. It is produced by RAE Systems by Honeywell. It displays in part per million (ppm). It has a size of 9.3cm by 4.9cm by 2.2cm and weighs 102g. It uses 2/3 AA high capacity Lithium battery and operates within a temperature of -40º to 55º C. it can be used in diverse applications such as oil and gas, chemical plants etc. Fig 3.3 ToxiRAE II (PGM 1100-series) 3.4.2 SELECTION OF MONITORING SITES In line with the objectives of this study, three monitoring/sampling sites were selected to represent all quarters of each study area. The sampling design used for choosing the sampling locations and points was the Purposive Sampling Method. Purposive sampling is a type of non- probability sampling technique which relies on the judgement of the researcher when it comes to selecting the units (e.g., people, cases/organizations, events, activities, pieces of data etc) that are to be studied. The main goal of purposive sampling is to focus on particular characteristics of a population that are of interest, which will best enable the researcher answer his research questions. Through careful observations, sampling sites or stations in the metropolis were identified prior to the dates of fieldwork. These sampling sites are areas of high traffic density in the metropolis. They are also majorly noted for high population within the study areas. The University of Lagos botanical and zoological garden acts as the control area. The control‟s location was chosen because of its remoteness and low traffic density. However, the three sampling locations for each study area were selected using the following criteria: 1. Presence of street vendors, shopping centers or kiosks with substantial presence of pedestrians. 2. Presence of adequate traffic density in order to characterize the significant air pollutants along the roadsides. 3. Absence of physical barriers that could impair the air sampling process. 4. Locating the sampling site in an industry free zone. This is used to exclude the industrial sources of pollution. 3.5 LIMITATION OF THE METHODOLOGY There is no research method that is free from limitations or bottlenecks. In this method, cost of administration, fees for field assistants are part of the limitations to the research study. Attitude of the respondents to the research questions may slowed down the pace of this research. This could be derived from the level of educational development of the respondents on the importance of research study. Cultural rigidity and level of social interdependence of the residents and occupants of shops could also hamper or promote the rate of progress in this research work. CHAPTER FOUR RESULTS AND DISCUSSION OF FINDINGS 4.1 RESULTS In this chapter, the data collected were analyzed based on the research questionnaires and sampling taken. These are presented in the form of figures and charts and the results obtained were discussed. A total of 120 copies of self-designed questionnaires were administered for both study areas: 60 for each study area. A total of 105 which represented 87.5% of the total number of questionnaire returned were used for the analysis. In Okota, 53 copies of the questionnaires were returned while 52 copies were returned for Surulere area. FREQUENCY 60 50 40 30 20 10 0 Okota Surulere RESPONDENTS Figure 4.1: Bar chart showing the relative size of study areas 4.1.1 DEMOGRAPHIC PROFILE OF THE RESPONDENTS The target population were residents of Okota and Surulere area. The questionnaire to collect data used for this study was designed in such a way that it had two sections; the first measured the demographic characteristics of the responents‟ perspective of pollutants and its impacts in the area. The data collected on demographic characteristics of the respondents were analyzed using desciptive statistics of frequency counts and percentage. A breakdown of the respondents‟ demographic characteristics are presented in tables below. 1) Age: The chart below presents the age distribution of the respondents. Their ages were measured with six categories. The age distribution of the respondents as shown in figure 4.2 indicates that age category 25 – 34 had the highest percentage representing 36.2% of the respondents. Age category 18 – 24 had 12.4%, category 35 – 44 had 32.4%, age category 45 – 54 represents 11.4%, category 55 – 64 had 5.7% while age category 65 and above represents the lowest percentage with 1.9% of the respondents. 40 35 FREQUENCY 30 25 20 15 10 5 0 18-24 25-34 35-44 45-54 55-64 65 and above RESPONDENTS' AGE Figure 4.2: Bar chart showing relative age distribution of respondents in both study areas. 2) Sex: In terms of gender distribution, figure 4.3 reveals that 55.2% of the sample were male while 44.8% were female. This implies that there were more male respondents than female respondents. 70 FREQUENCY 60 50 40 30 20 10 0 Male Female RESPONDENTS' GENDER Figure 4.3: Bar chart showing combined sex structure of respondents of both study areas. 4.1.2 PRESENTATION OF SELECTED RESEARCH QUESTIONS Six important questions out of over 40 questions that were used for the purpose of this study are analyzed here in. These questions focused on the respondents‟ knowledge of air pollution, the sources of pollution in the study areas, its effects on the quality of air, and rate of participation of respondents in pollution mitigation schemes. In order to answer these questions, descriptive statistics of frequency counts and percentage were used to analyze the data collected and the results obtained were presented in tables and charts. OKOTA STUDY AREA RESEARCH QUESTION 1 (DO YOU OWN A GENERATOR SET?) 45 40 FREQUENCY 35 30 25 20 15 10 5 0 Yes No RESPONDENTS Figure 4.4: Respondents‟ response to research question 1 The figure above reveals that 79.2% of the respondents affirmed ownership of either a big or small generator set while 20.8% indicated that they do not have a generator set at home. Based on the information from the respondents, it could be deduced that due to more people using generator sets, there will be contamination of the air with the exhaust fumes of the generator sets. Thus, affecting the quality of air they breathe in. RESEARCH QUESTION 2 (WHAT IS YOUR MEANS OF COOKING?) 25 FREQUENCY 20 15 10 5 0 Gas Cooker Electric Cooker Kerosene Stove Firewood Charcoal Gas Cooker and Kerosene Stove MEANS OF COOKING Figure 4.5: Respondents‟ respone to research question 2 Figure 4.5 shows that 24.5% of the respondents uses gas cooker only as a means of cooking and 1.9% of the respondents makes use of electric cooker. 43.4% opted for kerosene stove, 3.8% for charcoal while firewood has no user in the study area. From the data collected, it was also revealed that 26.4% of the respondents uses both gas cooker and kerosene stove. So based on this information, one can easily infer that the indoor air quality (IAQ) will not be of acceptable level since the highest percentage is of kerosene stove and this poses a great hazard to the quality of air they breathe in when indoor. RESEARCH QUESTION 3 (DO YOU OWN A DRIVABLE AUTOMOBILE?) 40 35 FREQUENCY 30 25 20 15 10 5 0 Yes No RESPONDENTS Figure 4.6: Respondents‟ respone to research question 3 From the above figure, it is revealed that 28.3% of the returned questionnaires indicates that they own and drive a car while 71.7% of them said they do not have a car. This information reveals that a lesser population of the respondents do not have a car, thus reducing the pollution of the air by vehicular exhaust. RESEARCH QUESTION 4 (HAVE YOU HEARD OF AIR POLLUTION?) 50 45 FREQUENCY 40 35 30 25 20 15 10 5 0 Yes No RESPONDENTS Figure 4.7: Respondents‟response to research question 4 The chart above reveals that 13.2% of the respondents have not heard of air pollution while 86.8% have heard of it. Based on this information, it could be deduced that a very large percentage of the respondents and inhabitants have a knowledge of air pollution, its sources, and likely effects but this knowledge does not necessarily equates the willingness of the inhabitants to curb or reduce the pollution caused by anthropogenic sources. RESEARCH QUESTION 5 (ARE YOU CONSULTED ADEQUATELY ON SCHEMES THAT MIGHT HAVE AN EFFECT ON AIR QUALITY?) Figure 4.8 below shows that there is no percentage of respondents who are consulted adequately on schemes relating to air pollution while 1.9% of the respondents are most of the times consulted. It also reveals that 13.2% are consulted on certain occasions and 24.6% of the respondents are barely consulted while 60.3% are not consulted at all. From this information gathered, it could be inferred that a higher percentage of residents are either hardly involved or not involved at all, therefore there is a very low participation of the residents of Okota in schemes carried out by governments which can affect the quality of air either positively or negatively. 35 FREQUENCY 30 25 20 15 10 5 0 Always Usually Sometimes Rarely Never RESPONDENTS Figure 4.8: Respondents‟ response to research question 5 RESEARCH QUESTION 6 (THE GOVERNMENT IS NOT DOING ENOUGH TO TACKLE AIR POLLUTION) Figure 4.9 reveals that 69.8% of the respondents agree that the government is not doing enough to tackle the menace of air pollution and 3.8% does not agree that the government is not doing enough while 26.4% can not say whether or not the government is not doing enough in tackling air pollution in Okota. It can be construed that there are inadequate regulations, policies, and rules to the subject of air pollution and also a minimal enforcement of already established policies. It can also be deduced that there are less public enlightenment and sensitization about air pollution. 25 FREQUENCY 20 15 10 5 0 Strongly Agree Agree Neither agree nor disagree Disagree RESPONDENTS Figure 4.9: Respondents‟ response to research question 6 Strongly disagree SURULERE STUDY AREA RESEARCH QUESTION 1 (DO YOU OWN A GENERATOR SET?) 50 45 FREQUENCY 40 35 30 25 20 15 10 5 0 Yes No RESPONDENTS Figure 4.10: Respondents‟ response to research question 1 The chart reveals that 84.6% of the respondents owns either a big or small generator set while 15.4% indicated that they do not have a generator set. Based on the information from the respondents, it could be deduced that due to more people using generator sets, there will be pollution of the air with the discharge fumes of the generator sets and this in turn affects the quality of air they breathe in. RESEARCH QUESTION 2 (WHAT IS YOUR MEANS OF COOKING?) 35 FREQUENCY 30 25 20 15 10 5 0 Gas Cooker Electric Cooker Kerosene Stove Firewood Charcoal Gas Cooker and Kerosene Stove MEANS OF COOKING Figure 4.11: Respondents‟ means of cooking From the above chart, it shows that 28.9% of the respondents uses gas cooker only as a means of cooking and 1.9% of the respondents makes use of electric cooker. 55.8% opted for kerosene stove, 1.9% for charcoal while firewood has no user in the study area. From the data collected, it was also revealed that 11.5% of the respondents uses both gas cooker and kerosene stove. So based on this information, one can easily infer that the indoor air quality (IAQ) might be polluted since the highest percentage is of kerosene stove and this poses a great hazard to the quality of air they breathe in when indoor. RESEARCH QUESTION 3 (DO YOU OWN A DRIVABLE AUTOMOBILE?) 18 16 FREQUENCY 14 12 10 8 6 4 2 0 Yes No RESPONDENTS Figure 4.12: Respondents‟ response to research question 3 Figure 4.12 reveals that 32.7% of the respondents indicated that they own and drive a car while 65.4% of them said they do not have a car and 1.9% did not fill in whether they own a drivable automobile or not. This information reveals that a lesser population of the respondents do not have a car, thus reducing the pollution of the air by vehicular exhaust. RESEARCH QUESTION 4 (HAVE YOU HEARD OF AIR POLLUTION?) Figure 4.13 reveals that 1.9% of the respondents have not heard of air pollution while 98.1% have heard of it. Based on this information, it could be deduced that a very large percentage of the respondents and inhabitants have a knowledge of air pollution, its sources, and likely effects but this knowledge does not necessarily equates the willingness of the inhabitants to curb or reduce the pollution caused by anthropogenic sources. 60 FREQUENCY 50 40 30 20 10 0 Yes No RESPONDENTS Figure 4.13: Respondents response to research question 4 RESEARCH QUESTION 5 40 35 FREQUENCY 30 25 20 15 10 5 0 Always Usually Sometimes Rarely RESPONDENTS Figure 4.14: Respondents‟ response to research question 5 Never Figure 4.14 shows that 3.8% of respondents are consulted adequately on schemes relating to air pollution while no respondents are most of the times consulted. It also reveals that 13.5% are consulted on certain occasions and 11.6% of the respondents are barely consulted while 71.1% are not consulted at all. From this information gathered, it could be inferred that a higher percentage of residents are either hardly involved or not involved at all, therefore there is a very low participation of the residents of Okota in schemes carried out by governments which can affect the quality of air either positively or negatively. RESEARCH QUESTION 6 (THE GOVERNMENT IS NOT DOING ENOUGH TO TACKLE AIR POLLUTION) 25 FREQUENCY 20 15 10 5 0 Strongly Agree Agree Neither agree nor disagree Disagree Strongly disagree RESPONDENTS Figure 4.15: Respondents‟ response to research question 6 Figure 4.15 reveals that 73.1% of the respondents agree that the government is not doing enough to tackle the menace of air pollution and 3.8% does not agree that the government is not doing enough while 23.1% can not say whether or not the government is not doing enough in tackling air pollution in Okota. It can be construed that there are inadequate regulations, policies, and rules to the subject of air pollution and also a minimal enforcement of already established policies. It can also be deduced that there are less public enlightenment and sensitization about air pollution. 4.1.3 EXISTING STATE OF THE AMBIENT AIR QUALITY OF THE STUDY AREAS The results of the air quality measurements taken from the three sampling locations for each study area (Okota and Surulere) are presented in tables and figure. The results were compared with the relevant Nigerian Ambient Air Quality Standards (NAQS) of the Federal Ministry of Environment and the air quality standards of the World Bank. 4.1.3.1 PRESENTATION OF OKOTA STUDY AREA AIR QUALITY MEASUREMENT CONCENTRATION (ppm) 30 25 20 15 CO SO2 10 NO2 5 0 Cele Bus Stop Ago Bus Stop Okota Roundabout SAMPLING POINTS Figure 4.16: Concentrations of gaseous pollutants (ppm) at Okota metropolis (Peak Period for dry season). CONCENTRATION (µg/m3) 120 100 80 60 PM 5 PM 0.5 40 PM 0.3 20 0 Cele Bus Stop Ago Bus Stop Okota Roundabout SAMPLING POINTS Figure 4.17: Concentrations of particulate matter (µg/m3) at Okota metropolis (Peak Period for dry season). The results for Okota metropolis during the traffic peak period hours at the dry season shows that gaseous pollutants exceeds the maximum allowable concentrations set by the Federal Ministry of Environment except for nitrogen dioxide (NO2) while the particulates‟ summation does not exceed the limit of 250µg/m3. The results for carbonmonoxide (CO) ranges from 7 – 28ppm, thus indicating that there is a high flow of vehicular traffic emission from vehicles plying ApapaOshodi Expressway and Okota-Ejigbo Road. According to Savile (1993), pollution due to traffic constitute up to 90 – 95% of the ambient CO levels. This is a very hazardous result for the health of man. Sulphurdioxide also passed the FMEnv limit of 0.1ppm. These levels suggests that there are activities in the area that leads to the emission of SO2. The results also indicates that NO2 level was not detected, thus indicating that no activity or processes that could emit appreciable amounts of this pollutant into the atmospheric environment. For the PM measured, this could be as a result of bad roads which frequently emit dust particles into the atmosphere. CONCENTRATION (ppm) 12 10 8 6 CO SO2 4 NO2 2 0 Cele Bus Stop Ago Bus Stop Okota Roundabout SAMPLING POINTS Figure 4.18: Concentrations of gaseous pollutants (ppm) at Okota metropolis (Off-Peak Period for dry season). 100 CONCENTRATION µg/m3 90 80 70 60 50 PM 5 40 PM 0.5 30 PM 0.3 20 10 0 Cele Bus Stop Ago Bus Stop Okota Roundabout SAMPLING POINTS Figure 4.19: Concentrations of particulate matter (µg/m3) at Okota metropolis (Off-Peak Period for dry season). The data collected for the trafic off peak period at Okota metropolis during the dry season reveals that the gaseous pollutants measured exceeds the Federal Ministry of Environment limit standards. Though the values can not be compared to that of the peak period because it drastically reduces. The reduction in these values can be attributed to the high flow of traffic and lesser vehicles on the road during these hours, thus resulting to lesser concentration of pollutants in the atmosphere. For the off peak period also, nitrogen dioxide (NO2) was not detected. The particulate matter varied between sampling locations. It was observed generally that the particulate matter also got reduced in the atmosphere during the traffic off peak period except for one sampling point – Ago bus stop and the summation was still within the limit. It was observed that the readings for Ago bus stop during the off peak period got increased and higher than that of the traffic peak period. . CONCENTRATION (ppm) 12 10 8 6 CO SO2 4 N02 2 0 Cele Bus Stop Ago Bus Stop Okota Roundabout SAMPLING POINTS Figure 4.20: Concentrations of gaseous pollutants (ppm) at Okota metropolis (Peak Period for rainy season). 90 CONCENTRATION µg/m3 80 70 60 50 PM 5 40 PM 0.5 30 PM 0.3 20 10 0 Cele Bus Stop Ago Bus Stop Okota Roundabout SAMPLING POINTS Figure 4.21: Concentrations of particulate matter (µg/m3) at Okota metropolis (Peak Period for rainy season). The results for the traffic peak period during the rainy season reveals that both gaseous pollutant and particulates concentrations were very low when compared to that of the peak period for dry season. The result for carbonmonoxide ranges from 4 – 10 ppm and this shows that the level did not go beyond the limit standard of 10ppm as set by the regulatory body, nitrogendioxide was not detected at all while sulphurdioxide was only detected in Cele bus stop and this can be attributed to emissions from vehicles plying the ever busy Apapa – Oshodi expressway and common combustion products. The detected particulates could be from dust re-suspension, vehicular emissions, and some domestic activities involving combustion from the shops and kiosks along Okota road. The lower concentrations of pollutants could be attributed to rain “wash out” effect in which air pollutants are removed or cleansed from the atmosphere by rainfall. 10 CONCENTRATION (ppm) 9 8 7 6 5 CO 4 SO2 3 NO2 2 1 0 Cele Bus Stop Ago Bus Stop Okota Roundabout SAMPLING POINTS Figure 4.22: Concentrations of gaseous pollutants (ppm) at Okota metropolis (Off-Peak Period for rainy season). 50 CONCENTRATION µg/m3 45 40 35 30 25 PM 5 20 PM 0.5 15 PM 0.3 10 5 0 Cele Bus Stop Ago Bus Stop Okota Roundabout SAMPLING POINTS Figure 4.23: Concentrations of particulate matter (µg/m3) at Okota metropolis (Off-Peak Period for rainy season). From the above figures, it is revealed that particulate matter (PM) concentration ranged as follows: 8.5 – 12.1µg/m3 for PM of size 0.3, 7.2 – 12.7µg/m3 for PM0.5 while PM5 has 10.1 – 47.5µg/m3. The ranges for other pollutants wre: N.D for sulphurdioxide (SO2), N.D for nitrogendioxide (NO2) while carbonmonoxide (CO) is from 1.3 – 9ppm. The observed gaseous and particulate pollutant levels were at background levels. Sulphurdioxide and Nitrogendioxide were not detected, so they were taken to be within their regulatory limits. In comparison to the results of the peak period during rainy season, it is observed that apart from the “wash out” effect of the rain, the free flow of traffic also reduces the concentration of pollutants in the atmosphere. During these off-peak hours, lesser number of vehicles ply the road and other anthropogenic activities leading to the release of pollutants have gotten reduced drastically, thus making the air more conducive for breathing at these periods. 4.1.3.2 PRESENTATION OF SURULERE AREA AIR QUALITY MEASUREMENTS CONCENTRATION (ppm) 14 12 10 8 CO 6 SO2 4 NO2 2 0 Ojuelegba Lawanson Itire SAMPLING POINTS Figure 4.24: Concentrations of gaseous pollutants (ppm) at Surulere metropolis (Peak Period for dry season). 90 CONCENTRATION µg/m3 80 70 60 50 PM 5 40 PM 0.5 30 PM 0.3 20 10 0 Ojuelegba Lawanson Itire SAMPLING POINTS Figure 4.25: Concentrations of particulate matter (µg/m3) at Surulere metropolis (Peak Period for dry season). The results acquired for Surulere metropolis during the traffic peak period at the dry season revealed that the CO levels were within the acceptable limit except for Ojuelegba bus stop that exceeded the limit of 10ppm. Averagely, the CO level is 8.7ppm and this is still within the limit. The concentration of SO2 ranges from 5.5 – 8ppm which greatly exceeds the federal ministry of environment limit of 0.1ppm and this poses a great hazard to the residents/occupants of the area. Nitrogendioxide was not detected in all three locations, thus indicating that there is no activity or processes leading to the emission of the pollutant. The particulates detected ranged as follows: 15.4 – 18.8 for PM of size 0.3, 12.6 – 16.6 for PM size 0.5 and 14.5 – 80.8 for PM of size 5. These levels detected could be as a result of the asphalt-tarred road which frequently emits dust particles which are lifted up by the wind into the atmosphere, and it is of importance to note that the three sampling locations are areas with high frequency of vehicles and pedestrians. 4.5 CONCENTRATION (ppm) 4 3.5 3 2.5 CO 2 SO2 1.5 NO2 1 0.5 0 Ojuelegba Lawanson Itire SAMPLING POINTS Figure 4.26: Concentrations of gaseous pollutants (ppm) at Surulere metropolis (Off-Peak Period for dry season). CONCENTRATION µg/m3 120 100 80 60 PM 5 PM 0.5 40 PM 0.3 20 0 Ojuelegba Lawanson Itire SAMPLING POINTS Figure 4.27: Concentrations of particulate matter (µg/m3) at Surulere metropolis (Off-Peak Period for dry season). The results for the off peak period of Surulere metropolis during the dry season shows that particulate matter (PM) concentration ranged from 11.4 – 13.3µg/m3 for PM0.3, 10 – 96.5µg/m3 for PM0.5, and 26.4 – 57.1µg/m3 for PM5. The ranges for other pollutants were: N.D for Nitrogendioxide (NO2), 3- 4ppm for Sulphurdioxide (SO2), and 1.1 – 4ppm for Carbonmonoxide (CO). According to the current effective national ambient air quality standards in Nigeria, the CO levels were at background level and still within acceptable limit. The levels for SO 2 reduced when compared to the values at the peak period but notwithstanding it was beyond the maximum allowable concentration of 0.1ppm and this poses a great risk for the residents of this area. The particulates detected also reduced based on the fact that there were lesser vehicles plying the Ojuelegba-Lawanson road. CONCENTRATION (ppm) 8 7 6 5 4 CO 3 SO2 NO2 2 1 0 Ojuelegba Lawanson Itire SAMPLING POINTS Figure 4.28: Concentrations of gaseous pollutants (ppm) at Surulere metropolis (Peak Period for rainy season). CONCENTRATION µg/m3 60 50 40 30 PM 5 PM 0.5 20 PM 0.3 10 0 Ojuelegba Lawanson Itire SAMPLING POINTS Figure 4.29: Concentrations of particulate matter (µg/m3) at Surulere metropolis (Peak Period for rainy season). From the results for the traffic peak period during rainy season for Surulere study area, the only notable gaseous pollutant is carbonmonoxide (CO). The pollutants were all within acceptable limit. Carbonmonoxide ranged between 0.7 – 7ppm, SO2 was only detected in Ojuelegba bus stop while NO2 was not detected in any sampling location. The concentration of SO2 in Ojuelegba could be attributed to the bad vehicles plying the road to Yaba and other areas. The particulate matter was also low when compared to other periods during the rainy season. The low levels of pollutants measured could largely be attributed to dilution and dispersion caused by rainfall. Rainfall also cleanses the atmosphere of emissions from natural and anthropogenic sources. CONCENTRATION (ppm) 1.4 1.2 1 0.8 CO 0.6 SO2 0.4 NO2 0.2 0 Ojuelegba Lawanson Itire SAMPLING POINTS Figure 4.30: Concentrations of gaseous pollutants (ppm) at Surulere metropolis (Off-Peak Period for rainy season). 45 CONCENTRATION µg/m3 40 35 30 25 PM 5 20 PM 0.5 15 PM 0.3 10 5 0 Ojuelegba Lawanson Itire SAMPLING POINTS Figure 4.31: Concentrations of particulate matter (µg/m3) at Surulere metropolis (Off-Peak Period for rainy season). The results for the off-peak period at rainy season for surulere study area shows the lowest concentration of pollutants measured for this project. Carbonmonoxide was detected in only two out of the three sampling locations with concentrations of 1.2ppm at Ojuelegba and 0.8ppm at Lawanson respectively. Sulphurdioxide and Nitrogendioxide were not detected in all sampling locations. Particulates ranged from 6.4 – 42.4µg/m3, thus having the least concentration of PM range so far. These levels are all within the acceptable limit as set by the regulatory body. The unappreciable concentration of CO and SO2 could be attributed to the regular supply of power during the period they were measured, thus eliminating or reducing the usage of power plants and generators in the neighbourhood. This is also accompanied by the “wash out” effect of the rain and lesser traffic of vehicles on the road during the period this period. The implication of this is that the levels observed do not pose any health hazards. 4.1.3.3 PRESENTATION OF CONTROL AREA AIR QUALITY MEASUREMENTS CONCENTRATION (ppm) 0.8 0.7 0.6 0.5 0.4 CO 0.3 SO2 0.2 NO2 0.1 0 Unilag Botanical Garden SAMPLING POINT Figure 4.32: Concentrations of gaseous pollutants (ppm) at Unilag Botanical Garden (Dry Season). CONCENTRATION µg/m3 14 12 10 8 PM 5 6 PM 0.5 4 PM 0.3 2 0 Unilag Botanical Garden SAMPLING POINT Figure 4.33: Concentrations of particulate matter (µg/m3) at Unilag Botanical Garden (Dry Season). CONCENTRATION (ppm) 0.4 0.35 0.3 0.25 0.2 CO 0.15 SO2 0.1 NO2 0.05 0 Unilag Botanical Garden SAMPLING POINT Figure 4.34: Concentrations of gaseous pollutants (ppm) at Unilag Botanical Garden (Rainy Season). CONCENTRATION µg/m3 12 10 8 6 PM 5 PM 0.5 4 PM 0.3 2 0 Unilag Botanical Garden SAMPLING POINT Figure 4.35: Concentrations of particulate matter (µg/m3) at Unilag Botanical Garden (Rainy Season). The University of Lagos‟ botanical garden was used as the control area for this project. Air parameters were measured during both seasons which serves as reference concentrations against which the results for the two study areas are compared. The concentration of CO was 0.7ppm while both SO2 and NO2 were not detected. The particulates ranged from 8.2 – 11.5µg/m3. During the rainy season, the concentration of CO was 0.36ppm while SO2 and NO2 were not detected as in the dry season. The particulates for this period ranged from 6.9 – 9.8µg/m3. All measured pollutants for both seasons were within the acceptable limit, thus indicating that the atmosphere in the control area does not pose any health hazard. This could be attributed to the very low traffic density in the area and also the presence of trees and shrubs planted along the area and inside the botanical garden which serves as carbon sink. 4.1.4 COMPARISON OF AIR QUALITY MEASUREMENTS WITH CONTROL AREA 18 CONCENTRATION (ppm) 16 14 12 10 CO 8 SO2 6 NO2 4 2 0 Okota Dry Season Okota Rainy Season Control Area SAMPLING POINT Fig 4.36: Comparison of Okota‟s gaseous concentrations with control area CONCENTRATION µg/m3 80 70 60 50 40 PM0.3 30 PM0.5 20 PM5 10 0 Okota Dry Season Okota Rainy Season Control Area SAMPLING POINT Fig 4.37: Comparison of Okota‟s particulates with control area CONCENTRATION (ppm) 9 8 7 6 5 4 CO 3 SO2 2 NO2 1 0 Surulere Dry Season Surulere Rainy Season Control Area SAMPLING POINT Fig 4.38: Comparison of Surulere‟s gaseous concentrations with control area CONCENTRATION µg/m3 70 60 50 40 PM0.3 30 PM0.5 20 PM5 10 0 Surulere Dry Season Surulere Rainy Season Control Area SAMPLING POINT Fig 4.39: Comparison of Surulere‟s particulates with control area The mean values for concentration of each of the parameters were calculated using the Microsoft Excel Spreadsheet computer program for repeated measurements and as well as to obtain a representative discrete value. The mean values of the concentrations for the six sampling locations were compared side by side with that of the control area as shown in the charts above. All measured pollutants for both seasons were within the acceptable limit at Unilag botanical garden, thus indicating that the atmosphere in the control area does not pose any health hazard. This could be attributed to the very low traffic density in the area and also the presence of trees and shrubs planted along the area and inside the botanical garden which serves as carbon sink. For Okota study area, the mean values of carbonmonoxide (17ppm) and sulphurdioxide (6.33ppm) during the dry season grossly exceeded the prescribed standards by the federal ministry of environment which are 10ppm and 0.1ppm respectively. This could be as a result of the high traffic density around Cele bus stop which is one of the sampling locations, absence of trees planted along roadsides etc. The rainy season‟s concentrations of carbonmonoxide (6.43ppm) and sulphurdioxide (1.2ppm) were within the set limit except for SO2 which slightly exceeded it. The particulates‟ mean values were all within the limit set by FMEnv. The Surulere study area mean values of carbonmonoxide for both seasons (8.17ppm and 3.33ppm) were within the limit while that of SO2 (6.75 and 0.8ppm) were higher than the standard limit. In comparison with the concentrations of the control area, it was observed that the concentrations posed serious health risks to individuals who spent long hours at these locations. Sensitive groups such as asthmatics, children and the elderly, people with heart or lung diseases were at highest risk. 4.2 DISCUSSION Average concentrations of CO, SO2, and PM of sizes 0.3,0.5, and 5µm obtained at both study areas and control area are as shown in figures 4.16 – 4.39. The results of air quality monitoring indicate high variability at different sampling locations depending on the density of mobile and stationary air pollution sources. Previous studies have assessed air pollution in different locations. Results from Zagha and Nwaogazie (2014) on the quality of air in Port-Harcourt indicated that the concentration vary at different sampling locations. The average concentration of Carbonmonoxide and Sulphurdioxide at Rumuola junction were 60.24ppm and 0.75ppm and this exceeded the USEPA hourly standards. In comparing their results to this current study, it can be said that air pollution were higher at Rumuola junction, since the results were higher than that of this study. This they reported could be as a result of the very slow movement of vehicles in that area. Another study on the ambient air quality by Oshuntogun (1999) at Ojuelegba and Mile 2 had the following reslts: Ojuelegba (CO:25PPM, SO2:1ppm) and Mile 2 (CO: 22ppm, SO2: NIL). These results were below the measured pollutants‟ concentrations gotten determined in this study. Okota recorded the highest concentration of CO of 28ppm and SO2 of 9ppm which could be attributed to the ever busy Apapa-Oshodi expressway that passes through Cele bus stop that happens to be one of the sampling locations for this study. This bus stop is known for her great congestion of vehicles whose emissions releases CO into the atmosphere, thus polluting the air. Also, Abdulraheem (2007) evaluated the air quality of Ilorin between every hour starting from 6:30am to 6:45pm. His results shows that the average concentrations of SO2 and NO2 were 7.17ppb and 2.03ppb respectively. The SO2 concentration was lower when compared to Okota and Surulere but revealed that the air is hazardous because of the presence of NO2, thus indicating that the areas of this current study are better cities in terms of NO2. From the questionnaires gathered, over 70% of the respondents in both study areas had encountered or frequently have cough, catarrh, and peppery eyes. This could be attributed to the higher concentration of CO and SO2 in both study areas. Associations between the distance from high-traffic roadways to residential areas and the prevalence of respiratory illness and symptoms have been found by a number of researchers. Mc Connell et al (2006) found that residing within 75m of a major road was associated with increased risk of asthma. This higher risk decreased to background rates at 150m – 200m from the road. Coogan et al (2011) also reports that there are plausible mechanisms by which the development of hypertension, systemic inflammation, automatic nervous system imbalance, and oxidative stress could be linked to particulate matter. With respect to the measurement of pollution exposure, there was an excellent exposure assessment, based on three monitoring sites per study area. Also, the questionnaire gave a deep insight into the residents‟ encounters with air pollution. overall, the results corrobate general relationships between air pollution, exposure, and health effects of respondents. Finally, based on increasing evidence on the pollution of the air we breathe in, there is need for recognition that this would be an appropriate issue to be considered by the Nigerian government. 4.3 EFFECTS OF MEASURED AIR POLLUTANTS The findings on the various analysis on the effect of air pollution on the study areas are discussed below. 4.3.1 MONITORING The analysis of air quality samples from the two study areas (Okota and Surulere) are discussed below. EXPOSURE Humans are exposed to air pollutants which give rise to air pollution always in the course of carrying out their day to day activities. Air pollutants which come in the form of gaseous emissions, particulates, and noise have the ability to cause life threatening illnesses which can result in short and long term ailments and eventually death. The rate at which humans are exposed to these air pollutants is based on the type of activity and environment within which they find themselves coupled with the degree they are exposed to. It also depends on the duration of exposure. Air pollutants can enter into the human body through different routes based on their characteristics which are size and shape. The exposure routes includes: Inhalation: Air pollutants can be inhaled through the nose due to the small particle size and their dustiness. The particles then accumulate in the trachea or the lungs resulting into respiratory problems such as chest pain or breathing difficulty. Ingestion: Air pollutants can be swallowed especially from food and vegetables consumed from farmlands containing excess nitrogenous fertilizers e.g. ammonia Absorption: The size and shape of air pollutants makes it easy for it to be absorbed by the skins of unsuspecting persons after it must have settled on their skins for a length of time. Air pollution comes with various risks and health problems. The result from the field measurements shows that the air pollutants among the measured gaseous pollutants that breached their various set limits by the federal ministry of environment that are of utmost concerns are Carbonmonoxide (CO) and Sulphurdioxide (SO2). Their origins come from vehicular emissions, use of generators, combustion of fossil fuels, and combustion of sulphur containing fuels. The health effects caused by these pollutants and the symptoms of ailments related to these air pollutants include breathing difficulty, wheezing, coughing, and skin outgrowth. These effects can result in increased medication use, increased doctor and emergency room visits, more hospital admissions and premature death. The human health effects of poor air quality are far reaching, but principally affect the body‟s respiratory system and the cardiovascular system. Individuals‟ reactions to air pollutants depends on the type of pollutant a person is exposed to, the degree of exposure, the individual‟s health status and genetics . CHAPTER FIVE CONCLUSION AND RECOMMENDATIONS 5.1 CONCLUSION Due to the ignorance of Nigerians on the fact that there exists a close nexus between urban air pollution and sustainable city, little or no attention is paid to the control of urban air pollution in Nigeria. In developing countries, the history of air pollution problem has typically been that of high levels of smoke coming from vehicular emissions, internal combustion engines, and industries. Sulphur dioxide arising from the combustion of sulphur-containing fossil fuels such as coal for domestic and industrial purpose also add to the pollution of the atmospheric air. It is based on this scenario that environmentalists foresaw that controlling pollution will become more difficult and complex in the near future if the current trend continues. It is therefore vital that for healthy and sustainable living, the preventive measures and sustainable solutions proffered to ensure safe environment for the population to live are considered and implemented. The sources of air pollution identified in the study also exposed the common channels of environmental pollution and its effects on the residents of Okota and Surulere. These sources include the use of diesel and petrol powered generators virtually in all homes due to the epileptic power supply condition in Nigeria. This could be the reason for higher levels of SO2 observed in the dry season when the power situation was worse. The transport induced air pollution is further compounded by daily influx of motorcycles, tricycles, and the importation of „tokunboh‟ vehicles. The lack of vehicular emission control also contributes to the pollution of the atmosphere. All these atmospheric problems had recieved little attention in Nigeria and have become a subject of increasing national interest and importance over the last few years. Though statutory and policy provisions regulating air pollution in Nigeria as well as Lagos state are in existence and are of lofty benefits, they have however over the years been overlooked and are of little or no strict implementation. Results of this study have confirmed that the dwellers or passers-by of Okota and Surulere metropolis were being exposed to high levels of the air pollutants (CO, SO2, PM). Persons at the University of Lagos botanical garden axis, away from high traffic density, were safer and enjoy a much healthier environment. The pollutant concentrations in this study were above established ambient air quality standards for some parameters depending on the traffic period and the season. It is reasonable to assume that certain road corridors will likely exceed these reported values in future, especially during the dry season and given the continued increase of vehicles in the metropolis. The present study revealed that there is a dire need to focus on air quality management in urban areas to safeguard the public health and the environment. 5.2 RECOMMENDATIONS The following are some of the recommendations to ensure that clen air quality is achieved in Okota and Surulere.  Review of Environmental Policies: There is a need for the reviewing of environmental policies, rules, regulations, plans, and programmes for air pollution. Strict punishment should thereforebe given for any breach of environmental laws.  Extensive Public Awareness/Sensitization: The public should be enlightened and sensitized on the sources of pollution, its hazard to human health and the environment coupled with personal efforts to curb the menace.  There should be an improved traffic control management in the study areas.  Strict Enforcement of existing legislations: The authority should ensure there is a constant strict enforcement of laws and legislations guiding air pollution in the state especially at the two study areas.  There is a need for an improvement in the power situation of the nation entirely which will in turn reduce the use of generators and risks involved in it.  Extensive Plantation: Trees should be planted regularly because they remove a significant amount of pollution from the atmosphere. 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Table 4.1: Analysis of the number of questionnaire administered Respondents Frequency Percentage (%) Okota 53 44.2 Surulere 52 43.3 Total 105 87.5 Table 4.2: Age distribution of the respondents Respondents‟ Age Frequency Percentage (%) 18 – 24 13 12.4 25 – 34 38 36.2 35 – 44 34 32.4 45 – 54 12 11.4 55 – 64 6 5.7 65 and above 2 1.9 Total 105 100 Table 4.3: Gender distribution of the respondents Respondents‟ Gender Frequency Percentage (%) Male 58 55.2 Female 47 44.8 Total 105 100 Table 4.4: Frequency and Percentage of the respondents‟ response to research question 1 (Okota Study Area) Variable Yes No Do you own a generator set? 42 11 79.2% 20.8% Table 4.5: Frequency and Percentage of the respondents‟ response to research question 2 (Okota Study Area) Variable Electric Kerosene Cooker Stove What is your 13 1 means 1.9% cooking? Gas Cooker of 24.5% Firewood Charcoal 23 0 2 43.4% 0 3.8% Table 4.6: Frequency and Percentage of the respondents‟ response to research question 3 (Okota Study Area) Variable Do you Yes own a No drivable 15 automobile? 38 28.3% 71.7% Table 4.7: Frequency and Percentage of the respondents‟ response to research question 4 (Okota Study Area) Variable Have you Yes heard of pollution? No air 46 7 86.8% 13.2% Table 4.8: Frequency and Percentage of the respondents‟ response to research question 5 (Okota Study Area) Variables Always Are you 0 consulted adequately on 0 schemes that might have an effect on air quality? Usually Sometimes Rarely Never 1 7 13 32 1.9% 13.2% 24.6% 60.3% Table 4.9: Frequency and Percentage of the respondents‟ response to research question 6 (Okota Study Area) Variable Strongly Agree agree The 15 government is 28.3% not Neither agree Disagree Strongly nor disagree disagree 22 14 1 1 41.5% 26.4% 1.9% 1.9% doing enough to tackle air pollution Table 4.11: Frequency and Percentage of the respondents‟ response to research question 1 (Surulere Study Area) Variable Yes No Do you own a generator set? 44 8 84.6% 15.4% Table 4.12: Frequency and Percentage of the respondents‟ response to research question 2 (Surulere Study Area) Variable Gas Cooker Electric Kerosene Cooker Stove What is your 15 1 means 1.9% of 28.9% Firewood Charcoal 29 0 1 55.8% 0 1.9% cooking? Table 4.13: Frequency and Percentage of the respondents‟ response to research question 3 (Surulere Study Area) Variable Do you Yes own a drivable 17 automobile? 32.7% No 34 65.4% Table 4.14: Frequency and Percentage of the respondents‟ response to research question 4 (Surulere Study Area) Variable Have you pollution? Yes heard of air 51 98.1% No 1 1.9% Table 4.15: Frequency and Percentage of the respondents‟ response to research question 5 (Surulere Study Area) Variables Always Are you 2 consulted adequately on 3.8% schemes that might have an effect on air quality? Usually Sometimes Rarely Never 0 7 6 37 0 13.5% 11.6% 71.1% Table 4.16: Frequency and Percentage of the respondents‟ response to research question 6 (Surulere Study Area) Variable Strongly Agree agree The 15 government is 28.9% not doing enough to tackle air pollution Neither agree Disagree Strongly nor disagree disagree 23 12 1 1 44.2% 23.1% 1.9% 1.9% Table 4.17: Concentration of Ambient Air Pollutants in Dry Season (Peak Period) Sampling CO SO2 NO2 PM0.3 PM0.5 PM5 Cele B/Stop 28 9 N.D 96 94.9 19.1 Ago B/Stop 7 4 N.D 11.3 10.7 16.5 Okota 16 6 N.D 10.6 94.7 66.9 Total 51 19 N.D 117.9 200.3 102.5 Mean 17 6.33 N.D 39.3 66.77 34.17 FMEnv 10 0.1 0.04 – 0.06 - - locations Roundabout - Limit ***Gaseous Pollutants are in ppm, PM are in µg/m3, N.D - not detected . Table 4.18: Concentration of Ambient Air Pollutants in Dry Season (Off-Peak Period) Sampling CO SO2 NO2 PM0.3 PM0.5 PM5 Cele B/Stop 11 4.5 N.D 15.4 13.0 42.3 Ago B/Stop 4 2.5 N.D 14.1 13.1 12.9 Okota R/A 4 4 N.D 10.2 86.7 34.4 Total 19 11 N.D 39.7 112.8 89.6 Mean 6.33 3.67 N.D 13.23 37.6 29.87 FMEnv 10 0.1 0.04 – 0.06 locations - Limit ***Gaseous Pollutants are in ppm, PM are in µg/m3, N.D - not detected . - - Table 4.19: Concentration of Ambient Air Pollutants in Rainy Season (Peak Period) Sampling CO SO2 NO2 PM0.3 PM0.5 PM5 Cele B/Stop 10 1.2 N.D 81 79.9 14.7 Ago B/Stop 4 N.D N.D 8.3 10.5 15.1 Okota R/A 5.3 N.D N.D 7.4 69.6 41.7 Total 19.3 1.2 N.D 96.7 160 71.5 Mean 6.43 1.2 N.D 32.23 53.33 23.83 FMEnv 10 0.1 0.04 – 0.06 - - - locations Limit ***Gaseous Pollutants are in ppm, PM are in µg/m3, N.D - not detected Table 4.20: Concentration of Ambient Air Pollutants in Rainy Season (OffPeak Period) Sampling CO SO2 NO2 PM0.3 PM0.5 PM5 Cele B/Stop 9 N.D N.D 8.5 12.7 10.1 Ago B/Stop 3 N.D N.D 12.1 7.2 47.5 Okota R/A 1.3 N.D N.D 10.1 9.0 23.6 Total 13.3 N.D N.D 30.7 28.9 81.2 Mean 4.43 N.D N.D 10.23 9.63 27.07 FMEnv 10 0.1 0.04 – 0.06 locations - Limit ***Gaseous Pollutants are in ppm, PM are in µg/m3, N.D - not detected . - - Table 4.21: Concentration of Ambient Air Pollutants in Dry Season (Peak Period) Sampling CO SO2 NO2 PM0.3 PM0.5 PM5 Ojuelegba 13 8 N.D 15.4 12.6 80.8 Lawanson 8 5.5 N.D 18.8 16.6 14.5 Itire 3.5 N.D N.D 17.5 14.9 84.9 Total 24.5 13.5 N.D 51.7 44.1 180.2 Mean 8.17 6.75 N.D 17.23 14.7 60.07 FMEnv 10 0.1 0.04 – 0.06 locations - - - Table 4.22: Concentration of Ambient Air Pollutants in Dry Season (OffPeak Period) Sampling CO SO2 NO2 PM0.3 PM0.5 PM5 Ojuelegba 4 4 N.D 13.3 10.0 26.4 Lawanson 4 3 N.D 12.9 10.8 57.1 Itire 1.1 N.D N.D 11.4 96.5 44.4 Total 9.1 7 N.D 37.6 117.3 127.9 Mean 3.03 3.5 N.D 12.53 39.1 42.63 FMEnv 10 0.1 0.04 – 0.06 locations - Limit ***Gaseous Pollutants are in ppm, PM are in µg/m3, N.D - not detected. - - Table 4.23: Concentration of Ambient Air Pollutants in Rainy Season (Peak Period) Sampling CO SO2 NO2 PM0.3 PM0.5 PM5 Ojuelegba 7 0.8 N.D 12.9 11.7 54.6 Lawanson 2.3 N.D N.D 9.7 8.7 11.2 Itire 0.7 N.D N.D 7.6 11.4 23.5 Total 10 0.8 N.D 30.2 31.8 89.3 Mean 3.33 0.8 N.D 10.07 10.6 29.77 FMEnv 10 0.1 0.04 – 0.06 locations - - - Limit ***Gaseous Pollutants are in ppm, PM are in µg/m3, N.D - not detected. Table 4.24: Concentration of Ambient Air Pollutants in Rainy Season (OffPeak Period) Sampling CO SO2 NO2 PM0.3 PM0.5 PM5 Ojuelegba 1.2 N.D N.D 6.7 8.0 11.6 Lawanson 0.8 N.D N.D 7.3 5.2 42.4 Itire N.D N.D N.D 6.4 18.9 21.1 Total 2 N.D N.D 20.4 32.1 75.1 Mean 1 N.D N.D 6.8 10.7 25.03 FMEnv 10 0.1 0.04 – 0.06 locations - Limit ***Gaseous Pollutants are in ppm, PM are in µg/m3, N.D - not detected. - - Table 4.25: Concentration of University of Lagos Ambient Air Pollutants (Dry Season) Sample Pt CO SO2 NO2 PM0.3 PM0.5 PM5 Botanical 0.7 N.D N.D 9.7 8.2 11.5 Garden ***Gaseous Pollutants are in ppm, PM are in µg/m3, N.D - not detected. Table 4.26: Concentration of University of Lagos Ambient Air Pollutants (Rainy Season) Sample Pt CO SO2 NO2 PM0.3 PM0.5 PM5 Botanical 0.36 N.D N.D 6.9 8.1 9.8 Garden ***Gaseous Pollutants are in ppm, PM are in µg/m3, N.D - not detected. Table 4.27: Comparison of Okota pollutants measurement with control area Pollutant Dry Season Rainy Season Control Area CO 17 6.43 0.7 SO2 6.33 1.2 N.D NO2 N.D N.D N.D PM0.3 39.3 32.23 9.7 PM0.5 66.77 53.33 8.2 PM5 34.17 23.83 11.5 ***Gaseous Pollutants are in ppm, PM are in µg/m3, N.D - not detected. Table 4.28: Comparison of Surulere pollutants measurement with control area Pollutant Dry Season Rainy Season Control Area CO 8.17 3.33 0.36 SO2 6.75 0.8 N.D NO2 N.D N.D N.D PM0.3 17.23 10.07 6.9 PM0.5 14.7 10.6 8.1 PM5 60.07 29.77 9.8 ***Gaseous Pollutants are in ppm, PM are in µg/m3, N.D - not detected.

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