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.
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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 MetropolitanArea 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)
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Table 1: Significance of Air Pollutants
NAME / PROPERTIES OF IMPORTANCE / SIGNIFICANCE AS AIR POLLUTANT+ / PHYSIOLOGICAL EFFECTS ON HUMANS*ACUTE EFFECTS / CHRONIC EFFECTS
1. Carbon Dioxide (CO2) / Colourless and odourless / Product of complete combustion of organic compounds, implicated in global climate change / - / -
2. Carbon Monoxide (CO) / Colourless and odourless / Product of incomplete combustion, toxic at high concentration / Asphyxiation, heart and brain damage, impaired perception. / Increased red blood cells (polycythermia) in blood, leading to increased resistance to blood to flow, weakness fatigue, and headaches.
3. Ozone (O3) / Very reactive / Damage to vegetation and materials, produced photochemical smog / Decreased pulmonary function and right-heart stress / Emphysema, fibrosis, right-heart failure, aging of lung and respiratory tissue.
4. Nitrogen Dioxide (NO2) / Brown or orange gas / Component of photochemical smog formation, toxic at high concentration / Incompletely understood, although cell membrane disruption appears to be the principal reason for respiratory tract edema. / Cell membrane damage and acid-induced irritation leading to or contributing to diminished pulmonary function and right-heart stress.
5. Nitric Oxide (NO) / Colourless, sometimes used in anesthetics / Produced during combustion and high temperature oxidation, oxidizes in air to NO2
6. Nitrous Oxide (N2O) / Colourless, used as aerosol carrier gas / 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 / 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. / 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.
8. Sulfur Trioxide (SO3) / Soluble in water to form H2SO4 / Highly corrosive
9. Hydrogen Sulphide (H2S) / Rotten egg odour at low concentration, odourless at high concentrations / Extremely toxic
10. Hydrocarbons (CxHy) / Many different compounds / Emitted from automobile crankcase and exhaust / The primary harm of hydrocarbons is in their participation in ozone production. / Cancer is one direct primary effect of some organic compounds.
11. Particulate Matters (SPM) / Effect varies depending on nature and size of particles. Can cause irritation, altered immune defense, or systematic toxicity. / Depending on the nature and size of the particles can cause decreased pulmonary function and stress on the heart.
+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 Within the System of Nature, 3rd Ed.Prentice Hall