Emissions of Vehicular Traffic Along Uhuru Highway Corridor in Nairobi

Abstract

Uhuru Highway Corridor is a road segment of the northern corridor (A8) in Nairobi city. It is one of the busiest and congestion-prone highways in Nairobi covering approximately 3.7 kilometers spanning between Lusaka roundabout and the museum hill interchange. The study investigated the urban ambient air pollutants levels correlation with vehicular emissions which included Carbon monoxide, (CO), Nitrogen dioxide (NOx), Sulphur dioxide (SOx), Total volatile organic compounds (TVOC), Hydrocarbons (HCHO) and Particulate matter of diameter 2.5 microns (PM2.5). A systematic study which measured CO, NOx, SOx, PM2.5, HCHO and TVOC in ambient air at two different stations, near Railway Underpass (NRU 01) and University of Nairobi Pedestrian Tunnel (UNPT 02) was done having variations in traffic flows and meteorology. Traffic flow was assessed with prevailing levels of emissions and the association of these air pollutants among each other. PM2.5. HCHO, SOx, CO and TVOC, all decreased with decrease in vehicle Volume. However, NOx which increased with decrease in vehicle. The ambient vehicular pollutions for the corridor were within the limits of World health organization (WHO) standards of (10mg/m3) with an exception on PM2.5 which was found to be 18.39mg/m3 and 18.56mg/m3 for stations NRU 01 and UNPT 02 respectively, CO values were 3.72ppm for NRU 01 and 3.76ppm for UNPT 02, SOx for the two stations NRU 01 and UNPT 02 were 0.37ppm. Volatile Organic Compounds (TVOC) for the stations were highest at NRU 01 at 0.36ppm and least at UNPT 02 at 0.32ppm. Nitrogen dioxide (NO2) was least at UNPT 02 at 0.32ppm and highest at NRU 01 at 0.50ppm. Sulphur dioxide (SO2) was 0.37ppm for the two stations NRU 01 and UNPT 02. To control this, an awareness campaign should be done by the Government to set up strict emission control standards to govern vehicle emissions and pollution. Key words: Traffic emissions, particulate matter, hydrocarbons, carbon monoxide, sulphur dioxide, total volatile organic compounds.