Air Pollution Mapping in Lagos

Air pollution is the third leading cause of death worldwide, and most large cities, have fine particulate matter (PM2.5) levels above WHO health guidelines. Here, we take a look air pollution mapping in Lagos to better understand the current situation, and where things may be heading. 

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Lagos became the capital of the British-controlled protectorate of Nigeria in January 1914, and has since become the largest city in West Africa, with an estimated metropolitan population of nearly 15 million. 

Naturally, its transformation came along with, and thanks to industrialization. From the year 1943 to 1959, pre-independence, a number of industries based around raw materials were flourishing, followed by the production of consumer goods like beer, soft drinks and cigarettes. Coal was the main source of energy until oil and gas were discovered in the early 1950s, and as is always the case, ignorance and hasty development led to damaging levels of pollution. .

Since then, sources of pollution have multiplied and magnified. Taking fine particulate matter (PM2.5) as a reference, the main emitters are road transport, heavy dependence on inefficient diesel and gasoline generators, poor waste management, construction and dirty fuels for household stoves. 

A lack of governmental leadership on the issue has resulted in a paucity of data concerning air pollution in Nigeria. With no official measurement stations nor standardized methods, it is difficult for officials to take informed and decisive action. Still, a number of independent operations have given indicative values for organizations to work with, and a few studies monitored PM2.5 over year-long periods in a few representative locations in Lagos. 

The result is an average 68 micrograms of PM2.5 per meter cube (mg/m3), around 7 times the WHO guideline value and in the range of other highly polluted megacities like Beijing and Cairo. Air pollution is very pernicious, because people living in it get used to the way the air feels and its effects manifest as a range of respiratory and cardiac disease, making it quite elusive. The truth is it’s health cost in Lagos alone was US$2.1 billion in 2018, or around 2.1% of Lagos State’s GDP. 

That translated to about 11,200 deaths in 2018 (the highest in West Africa), 60% of which were children under five years old. While they suffer mostly from lower respiratory tract infections, adults deal with heart disease, lung cancer and chronic obstructive pulmonary disease.

PM2.5 and cigarettes have very similar effects on human health, which is why Berkeley Earth calculated their equivalence, which we used to map the situation in Lagos. 

Air pollution mapping in Lagos. PM2.5 data from NASA-SEDAC (2016).

The worst of its pollution is spread over less densely populated areas, but in the city center, people are still breathing in the equivalent of over 5 cigarettes per week each year. 

It is imperative for such avoidable death and morbidity to be stopped, so let’s take a look at the sources and what can be done about it.

Road transport is the worst source of ambient air pollution in Lagos, unsurprising considering most vehicles are over 15 years old with old emission technologies and sulfur heavy fuels. The fix here is to implement vehicle emission standards with a progressive rollout to allow the population to adapt. Improving public transport also goes a long way. 

Industrial emissions are the second largest source. Zones with cement, chemical, furniture, refinery and steel activities are concentrated have wildly unhealthy levels of pollution – a PM2.5 concentration of 1,770 mg/m3 was once recorded over 24h in Odogunyan. This can be addressed by switching fuels, using modern energy recycling like combined heat and power, and recycling materials. Of course, this is expensive and requires heavy commitment. 

The next biggest problem is the fact that 50% of energy generation comes from private, diesel-powered generators because of how unreliable the energy grid is. This very poor combustion of gasoline and oil produce a lot of noxious fumes, especially when used indoors. Once again, this can be solved but requires a revamp of the grid, and therefore is more about money and commitment than anything else. 

The World Bank’s Pollution Management and Environment Health Program is campaigning to offer incentives and policies in collaboration with the Lagos State Government to help tackle the problem. There are opportunities for innovative investing in the area too thanks to initiatives like the IFC’s Breathe Better Bond that creates climate-friendly infrastructure projects. Still, it is the government’s job to take the lead, improve monitoring and take action for its citizens well-being. 

This article was written by Owen Mulhern.

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