Congested cities: The growing threat of poor air quality in Africa

Traffic in Kigali's city centre. The UN labels air pollution in African cities as an 'invisible danger'. Photos: David Renke/dpa

Business people in particular like catching a ride on Albert Nzigirimania's motorcycle.

"They like the smooth ride and that there's no jerking from changing gears," he explains.Nzigirimania, in his mid-40s, is one of roughly 30,000 motorbike taxi drivers in Rwanda's capital Kigali. A little more than a year ago, he decided to switch to electric.