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Toward cleaner urban air in South Asia: Tackling transport pollution, understanding sources

This Energy Sector Management Assistance Program (ESMAP) study was undertaken to provide technical input to support the region-wide process of developing and adopting cost-effective and realistic policies and efficient enforcement mechanisms to reverse the deteriorating trend in urban air quality in South Asia. It focused mainly on fine particulate matter, estimated to account for most premature mortality and illnesses caused by outdoor air pollution. Through stakeholder feedback, the study examined two areas where more information and policy analysis could complement ongoing activities on air pollution control: making vehicle emissions inspection more effective and understanding sources of small particulate matter.

Poorly maintained older technology vehicles contribute disproportionately to total vehicular emissions. A common approach to identifying gross polluters and ensuring that they are repaired or retired is a vehicle inspection and maintenance program. The analysis carried out in this study recommends that limited resources be concentrated on applying more robust (but also costly) test protocols to vehicle categories in large cities likely to contain a disproportionately large fraction of high annual-kilometer, gross polluters (for example, commercial diesel vehicles).

The ultimate goal of inspection and maintenance is to reduce human exposure to elevated concentrations of harmful pollutants. Where air pollution is not serious, the number of people exposed is not large, or for vehicles that are not driven many kilometers a year or do not pollute much (such as new gasoline vehicles), the benefit of testing vehicles would be much less limited, if not negligibly small.

The amount of information available on sources of fine particulate air pollution in South Asia is extremely small. This study carried out an analysis of ambient fine particulate matter in the three largest Indian cities. This represents one of the first detailed fine particulate matter source apportionment studies carried out in South Asia. The results indicate that there is no single dominant source, but rather three principal sources of particulate air pollution: vehicle exhaust, re-suspended road dust, and solid fuels, especially in cities with cold winters. This would suggest that vigorously pursuing control measures in the transport sector while leaving other sectors essentially untouched is less likely to result in a marked improvement in urban air quality
than if a multi-pronged approach addressing a number of sources is adopted.

Download the study here: Toward cleaner urban air in South Asia: Tackling transport pollution, understanding sources.


Image credit: Asian Development Bank