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. They increase the quality of air in the city and
its surrounding and should therefore be considered an integral part of any comprehensive
plan aimed at improving overall air quality.
Promoting the use of environment friendly alternative clean fuels.
Air pollution monitoring stations should be put in place in Lagos state.
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APPENDIX I
Tables of Results
The following tables of results were obtained for the experimental measurements taken.
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.