The new WHO database of worldwide air pollution measures it in two different ways, and as a result Onitsha, Anambra State, can lay claim to the unenviable title of world’s most polluted city, according to a data collected between 2011 and 2015, just released by the WHO.
According to the WHO, an air quality monitor there registered 594 micrograms per cubic metre of microscopic PM10 particles, and 66 of the more deadly PM2.5s.
Onitsha’s figures are nearly twice as bad as notoriously polluted cities such as Kabul, Beijing and Tehran and 30 times worse than London. Onitsha, say academics, is a textbook example of the perils of rapid urbanisation without planning or public services creating a sustained pollution assault on its water and air.
As a tropical port city which has doubled in size to over 1 million people in just a few years, it is frequently shrouded in plumes of black diesel smoke from old ships; it has no proper waste incineration plants; its construction sites and workshops emit clouds of dust and its heavy traffic is some of the worst in Nigeria.
A recent study of Onitsha’s water pollution found more than 100 petrol stations in the city, often selling low-quality fuel, dozens of unregulated rubbish dumps, major fuel spills and high levels of arsenic, mercury, lead, copper and iron in its water. The city’s many metal industries, private hospitals and workshops were all said to be heavy polluters emitting chemical, hospital and household waste and sewage.