Particulate matter and heavy metal content in air in the city of Nairobi

Abstract

Nairobi City has a population of over 1.5 million and is growing at a rate of about 70 persons per day. Various activities in the City such as construction work, industrial processes, use of unroadworthy cars, and dust blown off unpaved roads do contribute enormously to suspended particulate matter in the air. In this work, .!he analysis by gravimetric and Energy Dispersive X-ray Fluorescence (EDXRF) of the suspended particulate matter in the air in the city centre, Industrial Area and one residential area was done. The values of lead obtained (0.395-1.321 llg/m3) falls within the WHO recommendations, but compared to the values reported in some European countries, they are high. Most of the elements had low enrichment factors, EF, except for lead (EF 104-353), bromine \(EF 429-1533) and zinc (EF 14-79). The bromine and lead were highly correlated to the number of light vehicles (r=0.874 and 0.942 respectively). In addition the ratio by weight of Br:Pb ranged 0.309-0.535 while the correlation factor for Br to Pb was 0.951 leading to the conclusion that both elements came from the leaded gasoline.