Abstract:
Exhaust gas emission is a by-product of air and fuel combustion in vehicle engines. It is a 
crucial contributing factor to air and environmental pollution that authorities emphasize 
controlling to mitigate the health and environmental hazards to communities. This was an 
experimental investigation to ascertain the emission status of used vehicles used for 
transport in Tanzania, some on the verge of surpassing their allowable emission levels. An 
experimental research design was opted for in this study and data were collected 
experimentally and through observations. Gas analyzers and emission detectors were used 
to obtain emission data for the study, where cluster sampling was preferred and 403 
gasoline and diesel-powered vehicles were investigated for general inspection. The study 
found that engine size, year of manufacture, and kilometers of travel affected vehicle 
emission levels. The results were analyzed and compared with the allowable emission values 
in the Tanzanian standards.