Associate Professor of Environmental Health Sciences, University of Massachusetts Amherst
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Anyone who has stepped off an airplane in one of the major cities of the developing world has encountered profound and noxious air pollution. In New Delhi, Jakarta, Accra, Kathmandu and many other cities, diesel exhaust and burning garbage foul the air. The most serious concern is particulate matter (PM) – microscopic particles, much smaller than a human hair, usually produced when chemicals from fuel combustion react in the atmosphere. Once these particles form, winds can transport them over long distances. Read more.