What explains the increase of life expectancy in botswana

Actually, the increase in life expectancy in Botswana happened in the past (between 2000 and 2010 - in any case, the major reason was the decrease in infant mortality).

In the last years, since 2010 it has fallen again, mostly due to an increase in the occurence of AIDS and violent deaths such as road accidents. 

Air pollution: “combustion results in gases such as nitrogen oxides, nitrogen dioxide and particulates. the main causes of air pollution include transport, domestic combustion and industrial processes. pollutants from these sources can cause problems in the immediate vicinity and a distance away.”