City Lights Up, So does Pollution...

City Lights Spike Air Pollution : Discovery News: "The glow of city lights obliterates light-sensitive molecules that scrub the atmosphere by night, adding to the problem of air pollution, a new study shows.

Artificial lighting over the Los Angeles area is 10,000 times dimmer than sunlight, but it still cuts night-time atmospheric cleansing by up to 7 percent, say researchers with the National Oceanic and Atmospheric Administration, which flew aircraft over the region four times this summer to measure city light intensity.

The lights prevent production of a particular type of nitrogen-oxide molecule known as a nitrate radical, which forms from reactions of nitrogen dioxide with ozone. It bonds well with pollutants in the atmosphere, but breaks down quickly in the presence of light.

'It doesn't exist during the day,' said Stark. 'At night, it shows up. It reacts with pollutants and cleans them up.'"