PITTSBURGH, May 10 (UPI) -- Idling jet aircraft engines and sunlight can combine to make airports a far bigger threat to local air quality than previously recognized, U.S. researchers say.
Researchers at Carnegie Mellon University in Pittsburgh have found oil droplets emitted by idling jet engines can turn into particles tiny enough to readily penetrate the lungs and brain, ScienceNews.org reported Tuesday.
While Jet engines operating at high power levels throw off mostly solid particles, at low engine speeds, such as when a plane is idling at gates or on taxiways, emissions are mostly in the form of microscopic droplets.
Sunlight, the researchers said, can trigger chemical reactions on the oily microdroplets and gases in the air to generate solid particles.
"Driving this chemistry," Carnegie's Allen Robinson said, "was hydroxyl radical," an oxidant effective at catalyzing the breakdown of oily hydrocarbons.
"To create this hydroxyl radical, you need sunlight," he said.
This oxidation of the idling engine exhaust can generate 35 times more particles than the engine originally emitted, and 10 times what computer models have typically predicted, the research found.
Robinson said this could have a marked effect.
"If you're number 46 in line awaiting takeoff, you could spend an hour idling," he said.
