National Geographic News, Reporting Your World Daily

Monday, November 23, 2009

Photo: Mystery Ingredient Cleaning Earth's Atmosphere


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A thick haze of air pollution obscures the view across Hong Kong's Victoria Harbor in an August 19, 2004, photo.

Molecules called hydroxyl radicals naturally clean trace amounts of pollution from the air, but the process spews out toxic ozone. In June 2009 researchers announced that a mysterious substance is at work in China's Pearl River Delta that cleans the air without creating ozone.

Photograph by Anat Givon/AP