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Particulate Matter: Getting a Handle on Air Pollution's Tiny Killers

Mention particulate pollution, and most people think of soot from smokestacks and diesel buses. But another source of particles--which are linked to respiratory-disease deaths in many cities--is just as important: gases from evaporated gasoline, solvents in paints, and other sources that condense onto bits of dust. Scientists have been hard pressed to figure out how these particles form and interact. But now, on page 96, a team of researchers describes a mathematical model that predicts how these gases are transformed into particles. The model should help the U.S. Environmental Protection Agency--which is planning to issue its first fine-particle standards this summer--figure out how to reduce levels of these tiny killers.