Science / Medicine : Pollution From Trees

In Atlanta and certain other southern cities, trees may contribute more hydrocarbons to the formation of photochemical smog than do cars and factories, according to computer modeling studies conducted by researchers at the Georgia Institute of Technology. These emissions may doom the Environmental Protection Agency’s attempt to control pollution by restricting release of man-made hydrocarbons, the researchers said.

EPA should instead concentrate on reducing emissions of nitrogen oxides, another smog component for which few natural sources exist, according the researchers said last week in Science magazine.

Trees have long been know to emit hydrocarbons. The purplish haze over the Appalachian Mountains, also known as the Great Smokies, is caused by hydrocarbon emitted by trees. But repreated studies by EPA in the past have concluded that such natural hydrocarbons contribute little to smog formation.