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We only wish we were kidding: A new study has discovered that greasy hair may actually reduce the amount of ozone you breathe in. Although ozone in the upper atmosphere protects us from shriveling up under the sun's ultraviolet rays, ground-level concentrations of the gas can cause respiratory distress and even permanent lung damage.

Lakshmi Pandrangi and Glenn Morrison, two researchers from the University of Missouri, exposed eight washed and eight unwashed hair samples to ozone for 24 hours. They found that, on average, unwashed hair absorbs roughly seven times as much ozone as its freshly shampooed counterpart. Ozone is probably reacting with components of hair oil," Morrison tells New Scientist.

While a head of greasy hair could reduce your ozone exposure indoors, say the scientists, don't throw out your shampoo just yet. Pandrangi and Morrison also found that unwashed hair samples produced more secondary-reaction products, such as 4-oxopentanal-a respiratory irritant-because the ozone reacts with the hair oils. For the elderly and the sick, who are more vulnerable to the effects of air pollution, the duo recommends that indoor air be filtered to reduce ozone. ::New Scientist

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