Can Dirty Air Do The Ozone Layer's Job?

These days, practically all the news about the ozone layer is bad. Scientists have discovered that the now-famous hole over Antarctica is getting bigger and lasting longer each year, allowing more damaging ultraviolet light to reach the earth. And they know the stratospheric ozone layer is shrinking over the U. S. and other temperate-zone nations even in summer -- a trend that could mean more skin cancer and crop damage.

But when John E. Frederick of the University of Chicago and other scientists actually measure the amount of UV light reaching the ground, things don't look so dire. The dirty secret: pollution. New data from Frederick's team show that in some countries with bad air pollution, such as Japan, the amount of UV rays reaching the ground has actually decreased. And in the U. S., pollution has reduced the expected increase in damaging rays by 50%, on average, with greater amounts in smoggy urban areas. That's because increases in ozone-containing smog near the ground are counterbalancing decreases in the ozone layer far above the earth.

Of course, no one is suggesting that air pollution is a solution. Since ozone near the ground causes a wide range of health problems, such as lung damage, says Frederick, "the downside of pollution is greater than the upside."

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