Vehicular Emission (Air Quality) Monitoring Study
in Lagos, Nigeria
By Eugene O. Itua
INTRODUCTION
On October 12, 2006 residents around Lagos Metropolis woke up, to their wonderment,
to a hazy atmosphere which was very unusual to Lagosians and indeed to so many people.
Many were lost as to what was happening. Some schools, especially around Maryland, Ojota, Anthony and Ikeja, etc
had to shut down and sent the children home. Those in relevant departments or agencies could not come out with a
categorical statement as to what was happening. That it was smog! To date, no one can have been able to give the
figure of the number of persons that were injured by this incident which made breathing difficult.
Well, whether there were records of injury/death or not does not matter now. Of main concern to a number of us is
that this situation brought to reality that air pollution problem is very real and actual in Lagos! All along we have
been so obsessed with the one that is readily visible – the solid waste which has been a menace all around and is
seriously being tackled by the present crop of LAWMA Management.
.
It is instructive to quickly mention here that the city of Lagos was formerly the capital of Nigeria. Although, it is the
smallest of the Nigerian States in size, it is the commercial nerve of the country and has about 70 percent of the
nation’s industries and commercial activities. Virtually all industrial, commercial and residential activities in the state
rely on generators for electricity to power their machineries and pieces of electrical equipment. Thanks to NEPA, oh
no, PHCH who has made power outage her hallmark!
Also, in Lagos a passenger rail transport system exists, but it is underdeveloped and underutilized hence this has been
overtaken by private operated buses. It is said that about 40 percent of all new vehicle registration and total fuel
consumption in Nigeria take place in Lagos. There are about 2,600 km of roads in Lagos that are frequently
congested, with over 1 million vehicles plying the roads on a daily basis!
All these contribute greatly to air pollution in the city which has now been classified by the Federal Government as
“Mega.”
AIR POLLUTION AND SOURCES
In the definition of air pollution here, we are concerned with the things humans add to or put into the air. Air
pollution is thus the transfer of harmful amounts of natural and synthetic materials into the atmosphere as a direct or
indirect consequence of human activity. In simple words, air pollution is the dust, gas and droplets we stir up when
we do the things we do as human.
In urban centres generally, human-generated air pollution sources can be divided into mobile and stationary sources.
While the former includes automobiles, buses, trains, airplanes and other powdered modes of transportation sources,
the latter have to do with factories, incinerators, and other kinds of non-mobile sources
Today, mobile source emissions have tended to be the largest contributor to urban emission inventories in many
locations. It is instructive to note here that mobile sources tend to be much smaller, much more plentiful and much
more widely dispersed than stationary sources. For instance, in an EIA Study carried out by Mechelec Construction
(Nigeria) on behalf of Lagos Urban Transport Project (LUTP) in 1996, the profile of air pollution by type and source,
in Metropolitan Lagos, revealed that road traffic is the major source of air pollution.
This is quite understandable since, over 60 percent of all activities are carried out using motor vehicles supported
greatly by the use of two-stroke engine motor-cycles (“okada”) for public transport throughout the city. At least half a
million motor-cycle of them ply the nooks and crannies of the city.
The problem has been exacerbated by the relatively high numbers of old and poorly maintained vehicles, which were
imported into the country as fairly used cars popularly known as “tokumbo cars”.
Among the pollutants entering our air from automobile exhaust are nitrogen dioxide, volatile hydrocarbons, carbon
monoxide and particulate matter. The hydrocarbons and nitrogen oxides may react with sunlight to form smog.
Both petrol and diesel fuels consist of mixtures of a large number of hydrocarbons which vary according to the
manufacturer and to local geography and climate. Additives may also be present and these include lubricants, antirust
agents, antioxidants, pre-ignition preventers and anti-knock agents. Aromatic hydrocarbons are added to petrol to aid
refining. These inevitably give rise to a large number of hydrocarbon pollutants, also known as volatile organic
compounds.
The negative impact of all these pollutants could severe.
IMPACT OF AIR POLLUTION
Some notable impacts of air pollution include loss of life, chronic respiratory illness, cardiovascular defects, and
carcinogen. Other consequences of air pollution include corrosion, acid rain, soiling of fabrics, damage of crops and
other vegetation including damage to aesthetic values (Table 1).
MANAGEMENT OF VEHICULAR AIR POLLUTION
Air pollution remains a very actual problem throughout the Metropolitan Area of Lagos. Mobile source emissions
would continue to be the largest contributor to the urban emission inventories. In other words, automobiles would
continue to be an increasingly larger part of the problem. This is because; vehicular transportation would still
represent a key factor in the socio-economic progress of the state. However, paripasu, the numerous benefits of
motor vehicles transportation would also continue to be offset partially by the air pollution generated by motor
vehicles with the attendant health risk and hazards.
Unfortunately, at present, there is neither a legislative framework nor a set standard in the State to monitor emission
from mobile sources. The regulatory framework put in place by the Federal government through the then Federal
Environmental Protection Agency (FEPA) in 1991 is limited to emission generated through stationary sources. The
Ministry of Transport is working with the Ministry of Environment to set guidelines on vehicular emissions, but this
has not yet come to fruition.
Consequently, it has become quite important to understand the role of mobile source emissions on air quality through
well-designed studies. This information can provide important input for the formulation of effective air quality
management strategies.
It is in the light of this that the Lagos State Government through Lagos Metropolitan Area Transport
Authority (LAMATA) with the assistance of the World Bank stands out to be applauded. Why? Recently
LAMATA assigned a Consortium led by Messr Multiple Development Services Ltd the task to do Vehicular
Emission (air quality) Monitoring Study in Lagos. Other members of the Consortium include SEEMS Nigeria
Limited, Environmental Research Group of the University Of Agriculture, Abeokuta and Mosunmolu
Ltd.
The study which is for a period of 14months is expected to meet the following objectives:
i)
To raise public awareness and promote a better understanding of the characteristics of air pollution, its
related health effects and its principal sources;
ii)
To establish a participative and multi-sector process in the management of air quality;
iii)
To strengthen local capacity for air quality management through improved understanding of issues and
technologies;
iv)
To develop a consensus among concerned stakeholders around a plan of immediate and longer term
actions (policy, economic, administrative and technical) to improve air quality in the city of Lagos. Such
a plan will outline the measures to be implemented as well as the investments required particularly for
the improvements of urban transport and mobility most likely to help improve the urban air quality.
We look forward to the Consortium meeting up the set objectives.
Eugene O. Itua is an Environmental Consultant and the Secretary, Lagos Council of the Waste Management Society of Nigeria (WAMASON)
Email: eugeneitua@yahoo.com
Table 1: Significance of Air Pollutants
NAME
PROPERTIES OF
IMPORTANCE
SIGNIFICANCE AS AIR
POLLUTANT+
1. Carbon Dioxide (CO2)
Colourless
odourless
and
2. Carbon Monoxide (CO)
Colourless
odourless
and
3. Ozone (O3)
Very reactive
4. Nitrogen Dioxide (NO2)
Brown or orange gas
5. Nitric Oxide (NO)
Colourless,
sometimes used in
anesthetics
Colourless, used as
aerosol carrier gas
Produced during combustion and
high temperature oxidation, oxidizes
in air to NO2
Relatively inert; not a combustion
product
7. Sulfur Dioxide (SO2)
Colourless
gas,
intense acrid odour,
forms H2SO4 in water
Damage to vegetation, building
materials, respiratory system
8. Sulfur Trioxide (SO3)
Soluble in water to
form H2SO4
Rotten egg odour at
low
concentration,
odourless at high
concentrations
Many
different
compounds
Highly corrosive
6. Nitrous Oxide (N2O)
9. Hydrogen
(H2S)
Sulphide
10. Hydrocarbons (CxHy)
ACUTE EFFECTS
PHYSIOLOGICAL EFFECTS ON HUMANS*
CHRONIC EFFECTS
Product of complete combustion of
organic compounds, implicated in
global climate change
Product of incomplete combustion,
toxic at high concentration
-
Damage to vegetation and materials,
produced photochemical smog
Component of photochemical smog
formation, toxic at high concentration
Decreased pulmonary function and right-heart
stress
Incompletely
understood,
although
cell
membrane disruption appears to be the
principal reason for respiratory tract edema.
Asphyxiation, heart
impaired perception.
-
and
brain
damage,
Give rise to irritation reactions, which cause
capillaries to dilate and exude fluid; this leads
to tissue fluid accumulation and swelling
(edema), bronchial spasms, and shortness of
breath. General physiological reaction to SO2 is
similar to allergic asthma, i.e with impaired
pulmonary function via increased airway
resistance, impaired lung clearance, and
increased susceptibility to infection.
Increased
red
blood
cells
(polycythermia) in blood, leading
to increased resistance to blood
to flow, weakness fatigue, and
headaches.
Emphysema, fibrosis, right-heart failure,
aging of lung and respiratory tissue.
Cell membrane damage and acid-induced
irritation leading to or contributing to
diminished pulmonary function and rightheart stress.
Contributes to and aggravates lung
diseases
like
chronic
bronchitis,
pulmonary fibrosis via irritation leading to
decreased pulmonary function and
increase in stress on the heart.
Extremely toxic
Emitted from automobile crankcase
and exhaust
The primary harm of hydrocarbons is in their
participation in ozone production.
11. Particulate Matters
Effect varies depending on nature and size of
(SPM)
particles. Can cause irritation, altered immune
defense, or systematic toxicity.
+VESILIND, A.P. PIERCE J. J. AND WEINER R.F. (1990): Environmental Pollution And Control 3rd Ed.Butterworth-Heinemann. * = Kupchella, C, E & Hyland, M. C (1993): Environmental Science, Living
Cancer is one direct primary effect of
some organic compounds.
Depending on the nature and size of the
particles can cause decreased pulmonary
function and stress on the heart.
Within the System of Nature, 3rd Ed. Prentice Hall