Scientists Discover Unexpected Side Effect to Cleaning Up Urban Air

For decades, efforts to reduce air pollution have led to cleaner air in U.S cities like Los Angeles, with subsequent improvements in public health. Those efforts have targeted both nitric oxides and hydrocarbons. Hydrocarbons are emitted from many sources including gasoline-powered cars, trucks, solvents, cleaners used both at home and in industrial settings, and even trees.  Professor Paul O. Wennberg and colleagues have found that there is another chemical pathway for forming organic hydroperoxides—one that occurs at nitric oxide levels substantially higher than can be found in the atmosphere over unpopulated regions. "This is chemistry that does not exist in any of the models of how nitric oxide and hydrocarbons interact," says Professor Wennberg. [Caltech story]