Several non-profit organisations have launched a "Stop Flying Toilets" campaign in Kenya, using a winged logo and sponsoring races with famous Kenyan marathon runners.[7] The construction of three sanitation blocks (public toilets) in Kiambiu, a Nairobi slum with 40,000 to 50,000 residents, has reduced the use of flying toilets, and thereby reduced clogging in the drainage system and outbreaks of cholera and diarrhoea. The public toilets, constructed by the non-governmental organisation Maji na Ufanisi, based in Nairobi, require a fee to use, but have been quite popular.[8]