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Pollution threatens air quality

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A Car exhaust //Photo: BBC

A Truck exhaust //Photo: BBC

ON October 12, 2005, clouds of choking fumes enveloped the Lagos skyline for more than six hours, which heralded first-ever smog in Nigeria and a fresh insight into air pollution in the country.

The smog caused panic in the metropolis, with no official and tangible scientific explanation offered on the incident till date. But environmentalists say it was ‘nature’s red-light warning against the model of inefficient and blind development.’ But senior Lagos officials argued that it spurred decision-makers in the state to give environmental issues better attention.

It is a known fact that air pollution in Nigeria’s commercial capital does not discriminate among social classes. Researches revealed that Lagos’ 18 million residents inhale daily a deadly mix of Particulate Matter (PM), asbestos, Sulfur Dioxide (SO2), Nitrogen Oxide (NO), Carbon Monoxide (CO), and partially unburnt hydrocarbons.

These substances contribute to the death of seven million people – one in eight of total global deaths – as a result of air pollution exposure, according to new estimates by World Health Organisation (WHO), released recently. This finding more than doubles previous estimates and confirms that air pollution is now the world’s largest single environmental health risk. Reducing air pollution could save millions of lives.

In particular, the new data reveal a stronger link between both indoor and outdoor air pollution exposure and cardiovascular diseases, such as strokes and ischemic heart disease, as well as between air pollution and cancer. This is in addition to air pollution’s role in the development of respiratory diseases, including acute respiratory infections and chronic obstructive pulmonary diseases.

Findings by the Lagos Metropolitan Area Transport Authority (LAMATA) through its Lagos Air (vehicular emission) Quality Monitoring Study (LAQMS) published between 2007-2008, show that transport is a major source of air pollution in the city. Other sources included industries, dumpsites, open incinerators and power generators.

And in the United Kingdom, researchers have, for the first time, shown how exhaust pollution from diesel engines is able to affect nerves within the lung. Air pollution is a significant threat to health, they say, and identifying potential mechanisms linking exposure to diesel exhaust and the exacerbation of respiratory diseases may lead to treatments for those affected.

The concentration of NO, SO2 and CO exceeded the WHO guidelines at most location for in-situ measurement and 24-hour exposure. The mean concentration of NOx, SO2 and CO for instance was 31.5ppb, 28.6ppb and 11.9ppm respectively for 24-hour exposure. Particulate matter was 650μg/m3 while VOC (as BTEX) was 64ppbv. These values present great danger for the people.

Essentially, apart from transportation, other major source of air pollution in the city, include industries, dumpsites, open incinerators and power generators.  The study further reveals that the quantity of carbon dioxide in the environment presently is not only due to automobile emissions. It is affected by other factors such as electricity consumption, manufacturing and construction industries, petroleum refining as well as other chemical-based industries, and even residential areas. But the bulk of the entire quantity is contributed by the transportation sector.

For instance, the mean concentration of SO2 is highest at Oshodi and lowest at Imota. The maximum value of 84.3ppbv was obtained at Ikeja. This could be attributed to the number of trucks loading in this area. The 24-hour limit set by WHO is 47ppbv and 130ppbv for one-hour exposure. The limit was exceeded at a number of locations and the annual mean value in all the locations exceeded the WHO limit of 19ppb.

Ikotun environment had the highest value of NO2 among the eight locations sampled. The mean value of NO2 at CMS was however the highest closely followed by Ikotun while Unilag had the lowest value. The concentration of NO2 was high in February followed by January 2008. This could be attributed to the temperature gradient during this period of the year.

From the result of the profile of BTEX in the sampling areas, maximum concentration of the volatile organic compounds was at the highest ebb at Mazamaza and Maryland in January 2008. The concentration of BTEX at Imota and Ikotun were slightly lower than the mean highest values but greater than the value for Oshodi.

The results of measurements of the concentration of CO over the sampling period shows that the highest concentration of 6.0 ppm was detected at Ikotun and the lowest was recorded at Imota and Ikeja. Considering the average concentration over the entire period, Mazamaza, Oshodi and Ikotun had values that were higher the 3.0 ppm while CMS, Imota and Ikeja had values around 2.0 ppm.

The locations with relatively high value of CO are known to have heavy traffic at both peak and off peak hours and this could have accounted for the result obtained. Although the average concentration of CO at CMS was 2.0 ppm, the concentration rose to 3.2 ppm at a time and this could be attributed to occasional traffic hold-ups experienced in the area.

Compared with the World Health Organisation standards for 24-hour exposure (25 ppm), the results generally conformed to the standards in all the sampling locations. Although the result of one-hour measurement was higher in most of the locations, it however fell within the maximum limit of 100 ppm set by WHO.

The concentration of particulate matter followed the same trend for TSP, PM10 and PM2.5 at most of the locations. For example, with respect to PM2.5, Mazamaza had the highest mean concentration of 247.0μg/m3 and Unilag having the lowest concentration of 25.9μg/m3. Imota had the highest maximum concentration of 651 μg/m3 with Unilag having the least value of 63.4 μg/m3. The peak value PM2.5 was recorded in February 2008.

The result of receptor modeling conducted on the site shows that vehicular emission accounted for almost half of the total particulate matter emission apportioned within the area under study with about 43.3 percent. While emissions from the sea salt obtained a fair share of about 26 percent and the least pollutant source of PM (Biogenic Sulphur) contributes 0.6 percent. Biogenic Sulphur suspension in the atmosphere indicates the presence of wetlands (rivers, lagoons) in the area under study.

Another study by the team of Kayode John and Kamson Feyisayo, titled “Air Pollution by Carbon Monoxide (CO) Poisonous Gas in Lagos Area Southwestern Nigeria” noted that many Lagosians are suffering with heart-related diseases as a result of CO poisoning and Government is not showing serious concern in this part of the world.

The researchers examined exposure to air pollution caused by households’ wood burning of cooking, generating sets and vehicle emissions of CO poisonous gas in the most populated urban city of Lagos.

The researchers concluded: “Exposures to carbon monoxide at 100 ppm or greater are very dangerous to human health. Therefore, the level of carbon monoxide emission from commercial areas, residential areas, household kitchens and eateries is tolerable by the human system and considerably less threatening. Whereas CO emissions from petrol generators, diesel generators, cars, motorcycles and trucks depict a level of carbon monoxide that is highly toxic to human body, it is therefore advisable to avoid closeness to these sources.

“For as long as fossil fuels are being used to run automobiles; domestic generators, cooking and other related activities, carbon monoxide will be emitted into the environment thereby making it unsafe. From the results, automobiles dominate other sources of carbon monoxide within Lagos environs.

“The CO emissions from the domestic generators might not be unconnected to the rate at which families are wiped out due to fumes from generators kept within the flats or at an enclosure in the residential buildings.

“With this report, government needs to take decisive steps towards adequate enlightenment programme to educate the Nigerian people on the need to take ample preventive measures and curb the destruction to lives via this menace.”

Similarly, University of Lagos researchers, led by associate Professor of Pharmaceutical Chemistry, Dr. Chimezie Anyakora, in their study published last year in the FASEB Journal wrote: “The lack of constant electricity power supply to meet utility usage in developing countries like Nigeria has warrant the use of petroleum powered generators to supply electricity.”

The Covenant University researchers added: “All of the foregoing motivates this study to determine the level of human exposure to this deadly gas using Carbon Monoxide Detector so as to create the necessary adequate awareness of the quality of air within the metropolis whereby preventive measures could be put in place to curb the devastating effects on the innocent citizens, most importantly, the children.”

Anyakora and his team of researchers in another study published in Biomark Cancer established that generator fumes causes cancer. Meanwhile, researchers conclude they are 99 percent certain that hormone-altering chemicals are linked to attention problems, diabetes, other health problems even as they say that people living in areas with more air pollution face a greater risk of carotid artery stenosis, a narrowing of the arteries that supply blood to the brain.

Meanwhile, another new study suggests that exposure to traffic fumes could slow children’s progress at school. Scientists have linked pollution to lower cognitive development – a finding, which raises serious questions on Nigerian schools.

Researchers found primary pupils exposed every day to car fumes developed less quickly than children whose schools enjoyed cleaner air.

The findings, published recently in an international medical journal, PLOS Medicine, comes as the United Kingdom (U.K.) Government faces charges of breaking European Union (EU) laws on air quality.

Anyakora told The Guardian that, “due to the epileptic power supply, a lot of Nigerians has resorted into the use of petroleum powered generators to meet their daily utility usage. The inevitable use of these generator sets by almost every household increasingly constitutes nuisance to the environment and society at large. Coupled to its attendant noise and air pollution, generator fumes has been associated with the growing cases of cancers, premature birth, and changes in biochemical parameters like haematological disorder, liver disorder, kidney disorder, hormonal disorder, histopathological changes and sudden death.

“Generator fumes contribute significantly to the atmospheric level of Polynuclear Aromatic Hydrocarbons (PAHs) and PAHs have long been reported as the largest class of “cancer-causing” chemical compounds. This suggests a significant risk of cancer to the population in an environment where the use of generator is commonplace.”

“Excessive air pollution is often a by-product of unsustainable policies in sectors such as transport, energy, waste management and industry. In most cases, healthier strategies will also be more economical in the long term due to health-care cost savings as well as climate gains,” says Dr Carlos Dora, WHO Coordinator for Public Health, Environmental and Social Determinants of Health. “WHO and health sectors have a unique role in translating scientific evidence on air pollution into policies that can deliver impact and improvements that will save lives.”

In his presentation at the Lagos Climate summit recently, LAMATA’s Managing Director, Dr. Mobereola Dayo, said that vehicles contribute approximately 43 percent of ambient air pollution in Lagos. “The Nigerian vehicles are close to the Euro two standards, which is three to four times the European values.”

He disclosed that measures taken by the authorities include to monitor and measure air pollution in Lagos, development of the Lagos area Greenhouse Gas (GHG) emissions assessment manual to measure the impact of new transport initiatives on GHG.

In reaction, the Managing Director, Lagos Waste Management Authority (LAWMA), Mr. Ola Oresanya told The Guardian that efforts are being made to mitigate odours and reduce methane emissions from landfills in the metropolis.

He said the agency has introduced capping (greening), a scientific term for reducing the foul odour at the site by covering the whole site with laterite. Oresanya explained that LAWMA understands the plight of the people more than they could imagine.

The agency avoids burning the refuse because the air pollution would have a dangerous effect on the entire environment. Besides, the smoke could produce carcinogenic gases, which could cause lung infection for children and other airborne diseases.

Oresanya disclosed that the organisation has laid out the pipeline to capture gases from the refuse waste, because, if left uncaptured, the gases are self-combustible and could cause fire at the site.

The General Manager of Lagos State Environmental Protection Agency (LASEPA), Mr. Adebola Shabi, an engineer, said government is fully aware the effects of transportation and industrial activities on the metropolis.

According to him, Lagos is not the only place where the indicators are available. In any big city, such as Kano, Port Harcourt and other oil producing areas, the air quality is more polluted than Lagos.

“However, the government is doing all it could to ensure that Lagos air is safe. You cannot compare Lagos of today with what we had in 1999. Every administration has been on top of environmental issues. We have over two million vehicle on our roads, we are yet to start vehicular emission test.

“Air pollution through generator fumes are enormous and it constitute serious health hazard. Unfortunately, power supply is not vested on the state government, but rather, it is a Federal Government’s responsibility.”

Mr. Ryan Robinson, a PhD student at the National Heart and Lung Institute, Imperial College London, UK, informed the 13th European Respiratory Society Lung Science Conference about his work studying diesel exhaust particles and airway sensory nerves.

The news comes as the Healthy Lungs for Life campaign, launched by the European Respiratory Society and European Lung Foundation, takes place this year aiming to raise awareness of the importance of breathing clean air.

Diesel exhaust is a significant component of urban air pollution, containing a complicated mixture of gases and airborne particles. “Studies have shown that exposure to these diesel particles is associated with harmful health effects,” says Robinson.

“These particles are very small – down to 20 nanometres in diameter – and are therefore not only invisible to the naked eye, but can penetrate deep into the lungs.”

The lungs contain numerous sensory nerves that can detect potentially harmful stimuli and thus allow the body to respond, for example by triggering a cough. “However, we know that these nerves can also be involved in exacerbating respiratory conditions, for example by causing the bronchi to constrict in diseases such as asthma,” says Robinson.



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