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City Light Pollution

January 12, 2011

City lights may prevent the air from cleansing itself of pollutants.


Bright lights mean more smog. I’m Bob Hirshon and this is Science Update.

For years, stargazers have complained about city lights, because they make it impossible to see the stars. Now atmospheric chemist Harold Stark from the University of Colorado, Boulder, says the lights are also making it harder to see sights during the daytime, because they boost levels of ozone-based smog. He explains that the nighttime air normally cleans up ozone pollution, thanks to nitrogen based compounds that form after the sun goes down. But city lights interfere with these cleansers.

HAROLD STARK (University of Colorado, Boulder):
They destroy them, and they don’t allow them to basically process as much of these fuel molecules as they would during a dark night.

Since much of the chemistry happens high in the sky, doing a better job of pointing street lights downward could help clear the air. I’m Bob Hirshon for AAAS, the Science Society.