A model for estimating carbon monoxide emitted by vehicles in Nairobi

Abstract

SUMMARY Ground-level concentration of carbon monoxide emitted by vehicles in the city centre area of Nairobi is estimated. The method involves determination of vehicle emission rates based on emission characteristics of internal combustion engines and the use of the generalised Gaussian diffusion formula. The traffic volume applied to each street within the area under investigation is based on city council traffic engineer's department hourly motor vehicle count during the 1973-74 period. The results show that carbon monoxide (CO) is a significant air pollutant in the city centre although it has not yet reached those levels generally considered to be hazardous to human health. The highest concentrations are found in those areas where the traffic is heaviest and slowest. High concentrations are also found during the periods of light winds, CO dispersion being a strong function of wind speed.