Following the recent increase in attention on the health impacts of air pollution, there is a growing interest in understanding the different sources that contribute to population exposure. A new method developed by MAG offers an unconventional perspective on the origin of harmful pollution, especially in urban areas in developing countries .
In the past, local traffic and industry were often seen as the key sources responsible for the majority of harmful pollution in developing countries. A more comprehensive analysis, building on local monitoring data, comprehensive emission inventories, and available atmospheric dispersion models, however, suggests a much larger range of sources, especially for fine particulate matter, the most harmful air pollutant in developing countries. The important contribution of household fuel use (cook stoves) in cities and the surrounding areas is now well established, and global initiatives have been established to support universal access to clean energy.
However, a more comprehensive analysis has revealed other important sources that have received less attention in the past. These include open burning of municipal and agricultural waste; small industries and workshops whose emissions are often unregulated; and natural sources which are difficult to control. Strikingly, an important share of fine particles consists of secondary inorganic aerosols, which are formed in the atmosphere in the presence of agricultural ammonia emissions.
While the relative shares of the different sources depend on local conditions, the analysis clearly indicates that conventional air quality management strategies that often focus only on vehicle emissions are inadequate to realize the significant reductions in pollution that are required to achieve World Health Organization guideline values. Equally, the recent global efforts to provide access to clean household fuels will not suffice. A systems perspective is needed to produce a (cost-) effective intervention strategy that takes account of socioeconomic complexities of a wide range of other economic sectors, agriculture in particular.
Figure 1: The contributions to population exposure to fine particulate matter (PM2.5) in New Delhi in 2010 (* indicates that these estimates include contributions to secondary organic aerosols). Source: IIASA GAINS estimates (forthcoming)
 Kiesewetter GJ, Borken-Kleefeld J, Schöpp W, Heyes C, Thunis P, Bessagnet B, Terrenoire E, Fagerli H, et al. (2015). Modelling street level PM10 concentrations across Europe: source apportionment and possible futures. Atmospheric Chemistry and Physics. 15, 1539–1553.
Last edited: 01 March 2016
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