(CNN)The word "Africa" often evokes romantic images of elephants crossing the Kalahari, thundering water at Victoria Falls, or panoramic views from Table Mountain.

But an increasingly common sight for Africans -- especially those in Nigeria -- is that of smog, rubbish and polluted water, according to a new report.
Four of the worst cities in the world for air pollution are in Nigeria, according to data released by the World Health Organization (WHO).

Four of the worst cities in the world for air pollution are in Nigeria, according to data released by the World Health Organization (WHO).
Onitsha -- a city few outside Nigeria will have heard of -- has the undignified honor of being labeled the world's most polluted city for air quality, when measuring small particulate matter concentration (PM10).
A booming port city in southern Nigeria, Onitsha recorded 30 times more than the WHO's recommended levels of PM10.

Named and shamed
The other three cities named and shamed in the WHO report for high PM10 levels are the transport hub of Kaduna, in the north, which came fifth, followed by the cities of Aba -- in sixth place -- and Umuahia, in 16th position, which are both trade centers in southern Nigeria.

http://edition.cnn.com/2016/05/31/africa/nigeria-cities-pollution/

And the city with highest open defecation? The cities mentioned in southeast are commercial hubs with onitsha leading as the biggest market in West Africa.