Toxicologie environnementale et analytique

Air Quality Monitoring in Metropolitan Harare, Zimbabwe

Abstract

Mujuru M*,McCrindle RI,Gurira RC ,Zvinowanda CM,Maree J

Recent studies have linked air pollution in cities to chronic health problems like cardiovascular and cardio-respiratory deaths in the population. Pollution of the atmosphere in Harare, the capital of Zimbabwe, is a source of concern. In this study four pollutants (SO2, NO2, Pb, and total suspended particulate matter (TSPM)) were monitored at eight different sites scattered throughout the city for three months (July, August and September). SO2 was determined by bubbling the air into a solution of H2O2, followed by titration. The highest SO2 pollution of 820.0 μg/m3 was in an industrial area and the lowest pollution of 5.0 μg/m3 was in the Central Business District (CBD). SO2 pollution was generally above the World Health Organization (WHO) 24-hour guideline value of 125 μg/m3. NO2 was sampled from the air by passive samplers followed by spectrophotometric determination. The highest NO2 pollution was 46.14 μg/m3 at a site with a busy road nearby and the lowest was 11.09 μg/m3 in a high population residential area. NO2 pollution was generally lower than the WHO guideline value of 40.0 μg/m3 (annual mean). The total suspended particulate matter (TSPM) was determined as “black smoke” using the Soiling Index method. The highest total suspended particulate matter was 154.31 μg/m3 found in a high population density suburb located near some industries and lowest was 9.54 μg/m3 in a low density residential area which is far from pollution sources. Lead was determined by Graphite Furnace Atomic Absorption Spectrometry (GFAAS) for each month for every site and ranged from 0.01 to 0.72 μg/m3. The level of Pb pollution was highest in July and lowest in September at all sampling sites. A positive correlation was found between the levels of Pb and TSPM.