The Republic of South Africa, along with the Republic of Senegal is a leading example for Africa, for being the country with the most transparency on its Air Quality. The Air Quality monitoring network coverage is really good, and all the information is available publically and freely from the saaqis.org.za website.
Update June 4th 2015: The Air Quality data service from saaqis.org.za is temporarilly not available. We are now investigating, together with the South African Weather Service team responsible for SAAQIS, a solution for getting the data back online.