Air pollution, as been defined by World Bank, 1978 as ?the presence in the outdoor Atmosphere of one or more contaminants such as dust, fumes, gas, mist, odour, smoke, or vapour in such quantity, characteristics and duration as to make them actually or potentially injurious to human, plant or animal life, or property, or which unreasonably interferes with the comfortable enjoyment of life and property?. Pollution on the whole is caused principally by human activities, though it can also be a natural process. The major pollutants are generated from anthropogenic air pollutant, therefore when the smoke from the industrial cities of the nation becomes the smoke from burning furnaces in heavily populated cities like Lagos (Apapa, Amuwo Odofmoetc) Kano (Bompai), Port Harcourt gas flaring and refineries, Ibadan, the effects of pollution has become severe enough to alarm the inhabitants of these cities of the adverse effect of pollution (Otti, 2011).

MAJOR OCCURENCES OF AIR POLLUTION IN NIGERIA

Lagos is Nigeria?s most cosmopolitan city and most over-populated with an estimated population of 21,200,000 people especially migrants from the hinterland. It has a total area of 3,577.28 square kilometers, with wetland consisting of about 22% of the area and a population density of 5,926 persons per square kilometer (Oshodi, 2013). It was originated on the islands separated by creeks such as Lagos Island, protected from the Atlantic Ocean by sand spits like the Bar Beach. Lagos is the largest city in Nigeria. It is the main city of Lagos State and Nigeria?s main commercial centre, with more than 70% of the nation?s industries and economic activities. The city is also important to the rest of West Africa as a leading regional port and manufacturing centre with the highest number of multinational companies (Phillips and Horwood, 2007). The land mass of Lagos is almost occupied by both residential and industrial land uses, creating a congested environment for the people. Lagos accounts for about 40% of new vehicle registrations in Nigeria and it is the most industrialized with greenhouse gas emission. Sources of gas emission in Lagos are dump sites, open incinerators and power generators. Other notable sources of air pollution are the vehicular emission due to the increase in vehicles, industrial and commercial buses the use of chemicals, wastes and fossil fuel burning emanating from industries (Otti et al. 2011).

NIGER DELTA

The Niger Delta (Fig. 1) covers 20,000 km?within wetlands of 70,000 km?formed primarily by sediment deposition. Home to 20 million people and 40 different ethnic groups, this floodplain makes up 7.5% of Nigeria's total land mass. It is the largest wetland and maintains the third-largest drainage basin in Africa (Tawari and Abowei, 2012). The Delta's environment can be broken down into four ecological zones: coastal barrier islands, mangrove swamp forests, freshwater swamps and lowland rainforests. The region could experience a loss of 40% of its inhabitable terrain in the next thirty years as a result of extensive dam construction in the region. The carelessness of the oil industry has also precipitated this situation, which can perhaps be best encapsulated by a 1983 report issued by the NNPC, long before popular unrest surfaced: The Niger Delta witnesses slow poisoning of the waters destruction of vegetation and agricultural land by air pollutants which occur during industrial operations. But since the inception of the oil industry in Nigeria, >25 years ago, there has been no concerned and effective effort on the part of the government, let alone the oil operators, to control environmental problems associated with the oil and gas industry' (Baird, 2010) Nigeria flares more natural gas associated with oil extraction than any other country (Plate 2), with estimates suggesting that of the 3.5 billion cubic feet (100,000,000 m? of Associated Gas (AG) produced annually, 2.5 billion cubic feet (70,000,000 m?, or about 70% is wasted via flaring (Tawari and Abowei, 2012). This equals about 25% of the UK's total natural gas consumption and is the equivalent to 40% of the entire African continent's gas consumption in 2001. Statistical data associated with gas flaring are notoriously unreliable, but Nigeria may waste US$ 2. Billion/year by flaring associated gas (Baird, 2010). Flaring is done as it is costly to separate commercially viable associated gas from the oil. Companies operating in Nigeria also harvest natural gas for commercial purposes, but prefer to extract it from deposits where it is found in isolation as non-associated gas. Thus associated gas is burned off to decrease costs (Baird, 2010). Gas flaring releases large amounts of methane, which has a high global warming potential. The methane is accompanied by the other major greenhouse gas, carbon dioxide, of which Nigeria was estimated to have emitted more than 34.38 million metric tons of in 2002, accounting for about 50% of all industrial emissions in the country and 30% of the total CO2 emissions. While flaring in the west has been minimized, in Nigeria it has grown proportionally with oil production (Baird, 2010) The World Bank reported in 2004 that "Nigeria currently flares 75% of the gas it produces" (Marland et al., 2005). Gas flares have potentially harmful effects on the health and livelihood of the communities in their vicinity, as they release a variety of poisonous chemicals including nitrogen dioxides, sulphur dioxide, volatile organic compounds like benzene, toluene, xylene and hydrogen sulfide, as well as carcinogens like benzapyrene and dioxin. Humans exposed to such substances can suffer from a variety of respiratory problems (Tawari and Abowei, 2012). These chemicals can aggravate asthma, cause breathing difficulties and pain, as well as chronic bronchitis. Benzene known to be emitted from gas flares in undocumented quantities is well recognized as a cause for leukemia and other bloodrelated diseases. A study done by Climate Justice Estimates that exposure to benzene would result in eight new cases of cancer yearly in Bayelsa State alone (Marland et al., 2005). Whether or not flares contribute to acid rain is debatable, as some independent studies conducted have found that the sulphur dioxide and nitrous oxide content of most flares was insufficient to establish a link between flaring and acid rain. Other studies from U.S. Energy Information Administration (EIA) report that gas flaring is "a major contributor to air pollution and acid rain" (Bronwen, 1999).

SOURCES OF AIR POLLUTION

Air pollution in Nigeria is a public problem. Also indoor air pollution result from products used in construction like cement, asbestos roofing and ceiling sheet and inadequacy of general ventilation indirectly provokes some damages to human health. Moreover, industrial and mobile sources contribute enormously to air pollution that contaminate the ambient air, that surround us outdoor, the cement industries, Gboko in Benue, Nkalugu (Eboyi State) etc, the transport of this ambient air pollutant over large distance and their global impact has create enough effects on the environment and populace

In the Niger Delta area much of the pipeline explosions are a product of the later 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. Controlled wood fires in stoves and fireplaces can add significant amounts of smoke particulates into the air, inside and out (John, 1985). Indoor pollution fatalities may be caused by using pesticides and other chemical sprays indoors without proper ventilation.

The quality of air in Nigeria?s largest oil refinery (PHRC) and petrochemical complex (EPCL) was assessed based on key priority pollutants in a study carried out by Ana et al. (2009) (Plate 6). Three points each were observed per industrial location At the refinery, the highest PM10 "Stationary Sources" include smoke stacks of power plants, manufacturing facilities (factories) and waste incinerators, as well as furnaces and other types of fuel-burning heating devices

• "Mobile Sources" include motor vehicles, marine vessels, aircraft and the effect of sound etc.,

• Chemicals, dust and controlled burn practices in agriculture and forestry management. Controlled or prescribed burning is a technique sometimes used in forest management, farming, prairie restoration or greenhouse gas abatement. Fire is a natural part of both forest and grassland ecology and controlled fire can be a tool for foresters. Controlled  burning stimulates the germination of some desirable forest trees, thus renewing the forest

• Fumes from paint, hair spray, varnish, aerosol sprays and other solvents

The indoor air pollution occurs inside homes, school and offices, as results from product of use in construction material and emission of Nitrogen oxide, and sulphur oxide in air-conditioned houses, gas stove and some volatile organic compounds like Alkanes and furmaldchyde. In cities like Nkalagu, Gboko, Lagos, Kano, PortHarcourt and Ibadan, across Nigeria, acid rain and ozone pollution create an environmental impact and affect human health unknowingly as a result of cement factories located in these areas, some outdoor pollution consist of natural contaminants such as pollen, fungi spores, smoke, dust particles from forest fires (Otti et al. 2011).

• Waste deposition in landfills, which generate methane. Methane is not toxic however, it is highly flammable and may form explosive mixtures with air. Methane is also an asphyxiant and may displace oxygen in an enclosed space. Asphyxia or suffocation may result if the oxygen concentration is reduced to below 19.5% by displacement

Biomass combustion: Biomass in form of firewood, coal, bamboo trunks and dead leaves are commonly used sources of cooking fuel in the region. Of all these the most frequently used is firewood. This fuel woods are usually logged from nearby bushes and forests o are collected as dead branches within the residential vicinities by the women and sometimes children and are used to generate energy for cooking (Plate 3). 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 VOCs and particulate matter.

IMPACT

The potential of sea level rise to alter the living conditions of the half of the world?s population in the coastal zones and the constant risks of flooding have been reported (Townsend, 2002). In recent times, the extreme and unusual rains in Lagos have resulted into flooding, especially in the coastal regions of the state. It is one of the major environmental hazards now being faced by the mega city, threatening lives and properties (Oshodi, 2013). According to The Guardian (Editor, 2012), between July and October, 2011 alone, at least 7 major floods were witnessed killing about 30 people and destroying many properties. Also in 2012, heavy rains caused an unusual flooding that displaced thousands of people from their homes, with inhabitants of Islands and poorly constructed structures badly affected (Oshodi, 2013)

Cases of respiratory diseases and even death have been reported in Lagos (Ogunbi et al., 1978Olowoporoku et al., 2012). An epidemiological study by (Olowoporoku et al., 2012) showed a growing evidence of relationship between air pollution and mortality, hospital admissions for respiratory or cardiovascular disease and an associated increased risk of myocardial infarction in Lagos. The study revealed that the increasing rate of heart diseases and infections in most hospitals is as a result of the pronounced air pollution in the state

Loss of Biodiversity:

The continual generation of air pollution contributes to acidification of coastal waters and indirectly affects the underground water. The salinity of Lagos surface and underground water due to pollution has been reported (Olufemi et al., 2010) this has great effect on human and the aquatic organisms.

Effects on children: Cities around the world with high exposure to air pollutants have the possibility of children living within them to develop asthma, pneumonia and other lower respiratory infections as well as a low initial birth rate. Protective measures to ensure the youths' health are being taken in cities such as New Delhi, India where buses now use compressed natural gas to help eliminate the ?pea-soup? smog (Fuggle, 2004). Research by the World Health Organization shows there is the greatest concentration.

According to Environmental Rights Action and Climate Justice Programme, gas flaring is responsible for about 49 premature deaths, 5000 respiratroy illness, 120, 000 asthma attack and 8 additional causes of cancer each year.

EFFORTS TO COMBAT AIR POLLUTION

The Nigerian government came up with different initiative to combat air pollution especially the pollution caused by the use of fossil fuel.

The procurement and distribution of clean cooking stove to reduce pollutants is believed to stop the felling of trees for firewood and inhalation of smoke that has led to the death of about 90,000 women annually. Apart from reducing smoke, it will also reduce the effects of deforestation. Also, the Great Green Wall project, which involveds planting of several kilometeres of trees, launched in the Northern part of the country for the control of desertification will indirectly purify the atmosphere.

In Addition, the World Bank is currently supporting a rapid bus system in Lagos that is helping to take cars off the road and make transportation more efficient.

Furthermore, the Nigerian government has recently pledged to improve environmental health by 2020 at the Pollution Management and Environmental Health Program. It is also believed by Industry experts that the full and effective enforcement of Petroleum Industry Bill (PIB) will go a long way in controlling the activities of oil companies and minimize environmental pollution.

In Conclusion, Nigeria?s contributions to global greenhouse gas emissions are high due to its rapid population growth and energy consumptions. Although it is a great challenge for a country whose economy largely depends on fossil fuels to cut down its carbon emission, it becomes highly imperative to mitigate in order to avoid future hazards.

 

 

REFERENCES

Ana, G.R., K.C. Mynepalli, E.E. Sridhar and E.A. Bamgboye, 2009. Environmental risk factors and health outcomes in selected communities of the Niger Delta Area, Nigeria. Perspect. Public Heal., 129(4): 183-191.

Baird, J., 2010. Oil's Shame in Africa. Newsweek, 27. (July 26, 2010).

C.C. Tawari and J.F.N. Abowei Air Pollution in the Niger Delta Area of Nigeria  International Journal of Fisheries and Aquatic Sciences 1(2): 94-117, 2012

Editor, G., 2012. Taming the floods in Lagos. The Guardian.

Marland, G., T.A. Bnousoden and R.J. Andres, 2005. Global, Regional and National CO2 Emission. In Trends: A Compendium of Data on Global Change, Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee.

Olowoporoku, A., J. Longhurst and J. Barnes, 2012. Framing Air Pollution as a Major Health Risk in Lagos, Nigeria. In: Air Pollution XX, Brebbia, C. And J. Longhurst (Eds.), Southampton and Boston: WIT Press, ISBN-10: 9781845645823, pp: 479-486.

Ogunbi, O., H.O. Fadahunsi, I. Ahmed, A. Animashaun and S.O. Daniel et al., 1978. An epidemiological study of rheumatic fever and rheumatic heart disease in lagos. J. Epidemiol. Commun. Health, 32: 68-71. DOI:10.1136/jech.32.1.68

Otti Victor I, Nwajuaku AI and Ejikeme RI The Effects of Environmental Air Pollution in Nigeria VSRD International Journal of Mechanical, Auto. & Prod. Engg. Vol. 1 (1), 2011

Oshodi, L., 2013. Flood management and governance structure in Lagos, Nigeria. Regions Magazine, 292: 22-24. DOI: 10.1080/13673882.2013.10815622

Phillips, T. and C. Horwood, 2007. Tomorrow?s Crises Today: The Humanitarian Impact of Urbanisation. 1st Edn., Illustrated, Nairobi, Kenya, OCHA/IRIN, ISBN-10: 9211319641, pp: 112

Townsend, M., 2002. Environmental refugees. Ecologist,32: 22-25.