Spatial Variability of Ambient Air Pollution Concentration in Dar es Salaam

Robert M. Njee^{1, 2,} , Kees Meliefste³, Hamisi M. Malebo² and Gerard Hoek³

¹Preventive Health Department, Ministry of Health and Community Development Gender Elderly and Children, P.O. Box 9083, Dar es Salaam, Tanzania

²Department of Traditional Medicine, National Institute for Medical Research, P.O. Box 9653, Dar es Salaam, Tanzania

³Institute for Risk Assessment Sciences, Utrecht University, P.O. Box 80178, 3508 TD Utrecht, the Netherlands

Cite this paper:
Robert M. Njee, Kees Meliefste, Hamisi M. Malebo and Gerard Hoek. Spatial Variability of Ambient Air Pollution Concentration in Dar es Salaam. Journal of Environment Pollution and Human Health. 2016; 4(4):83-90. doi: 10.12691/jephh-4-4-2

Abstract

Epidemiological evidence shows health effects of ambient air pollutants. Such effects have been evaluated in different regions of the world but scarcity of pollution measurements in Sub Saharan Africa (SSA) limits understanding of pollution levels and related health risks. Our aim was to assess spatial variability of concentrations of key air pollutants in a major African city. Particles smaller than 2.5 and 10 µm (PM_2.5 and PM₁₀), the absorbance of PM_2.5, and NO₂ / NO_x were measured in dry season at locations close to identified pollution sources. Higher PM₁₀, PM_2.5 and soot concentrations were measured compared to typical European concentrations. NO₂ concentrations were moderate. PM₁₀ ranged from 86 µg/m³ at the urban background to 248µg/m³ at the landfill site, likely related to unpaved roads. PM_2.5. varied from 27µg/m³ at the harbor site to 49µg/m³ at the traffic site. Measured PM_2.5 concentrations were several times higher than the global 2005 modelled values based upon satellite and chemical transport modelling. PM₁₀ and PM_2.5 concentrations were 1.8 and 1.6 times higher at the traffic site compared to the urban background, a larger contrast than in most western studies. Suburban PM₁₀, PM_2.5 and soot absorbance concentrations were higher than at central urban location. The high soot concentrations document that combustion sources including motorized traffic contribute to the high PM concentrations. Average NO₂ concentrations ranged from 8 µg/m³ to 109 µg/m³. Emissions from road traffic vehicles were shown to have the strongest influence on all ambient pollutants, although emissions levels where roads were unpaved were associated with elevated levels of particulates. Spatial variability of particulate matter air pollution was larger and showed different patterns than reported in European / North American study areas. Ambient pollution monitoring with mitigation measures targeting road traffic emissions are necessary in averting negative health consequences of ambient pollution in SSA cities.

Keywords:
ambient air pollution concentration variability Africa.

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