Measurement of some air pollutants in selected Areas of Nairobi and its environs, and in other Selected industrial sites

Abstract

A six-month field study was conducted in which air samples of known volume were scrubbed through specific trapping solutions at selected sites in Nairobi (Chiromo, Industrial Area and Kasarani), Nderi shopping centre, Muguga and Thika Town. The solutions were then subjected to analysis for nine pollutants sulphur dioxide (S02), ammonia (NTh), hydrogen chloride (HCI), aluminium (AI), lead (Pb), cadmium (Cd), zinc (Zn), iron (Fe) and copper (Cu) using a variety of spectrophotometric and potentiometric techniques. The objectives of the study were (1) to determine the levels and distribution of these pollutants in ambient air, and (2) to determine the level of influence of industrial activity (flue gas emissions) on the concentrations of the pollutants in ambient air. There were wide variations in the distribution, occurrence and level of each pollutant at the sampling sites. S02, NIL and HCI were detected at all sites, the lowest concentration being at Kasarani which recorded 9.11, 22.4 and 386 ug m", respectively and highest at sites in Industrial Area (85, 449 and 2426 Ilg p1-3, respectively). These values differed considerably from those for the typical flue gases (emanating from furnace operations at Magadi and Gilgil) whose mean concentrations were 1374, 617 and 235 Ilg m", for S02, HCI and Nlli, respectively.