Newswise - Los Angeles and other big American cities aren?t the only places with smog problems. On December 7, Iran declared a smog emergency because the air was so bad in Tehran. That?s the bad news?the good news is that researchers have discovered that natural chemical processes in the atmosphere may be removing smog and other damaging hydrocarbons at a faster rate than once believed.
On December 7, as a thick, brownish yellow haze settled on the city of Tehran (which has 10 million people), residents told not to go to work or school for two days. Police prevented cars without a special permit from entering large parts of the city.
The government is threatening to restrict driving to only a few days a week, with those who have odd numbered license plates being allowed to drive some days and those with even numbered plates on others. They also may institute smog checks on cars. All this sounds familiar to Californians. Another familiar problem is that Tehran is too spread out to have an adequate public transportation system. Gasoline prices are subsidized, as it is in most of the Middle East, at about 34 cents a gallon, so driving is inexpensive and residents use their cars even short trips. Pollution alerts are becoming more common and the air quality is unhealthy about 100 a year. There has been an increase in asthma and allergies.
But we may yet be saved: scientists report that naturally-occurring atmospheric chemicals react with sunlight more effectively than scientists previously thought, breaking down smog and other pollutants after they absorb energy from sunlight. These natural air cleaners are called OH (oxygen-hydrogen) radicals.
Much of the hydrocarbon pollutants pumped into the atmosphere by humans result from burning organic matter such as wood or fossil fuels. The atmosphere has three main ways to cleanse itself of such pollutants. Two are relatively direct: water droplets in clouds absorb and rain them out of the atmosphere or sunlight breaks the molecules apart.
"The third way is the one we are concerned with here, the way that involves breaking these hydrocarbons down chemically," says climate researcher Joseph Francisco. "For that, the atmosphere relies on a reactive group of chemicals called OH radicals that attach themselves to hydrocarbons and rip them into inert pieces. We now theorize that the atmosphere may produce up to 20% more OH radicals than we once thought. We now have a better understanding of an atmospheric process that could be giving our pollution-weary lungs more breathing room."
Chemist Amitabha Sinha says, "It could be the atmosphere is more effective at breaking down pollution than models have shown. [However], we are out of the woods with regard to atmospheric pollution. What it means is that we need to do a much more careful job with our measurements in order to accurately account for all sources of OH radicals present in the air." OH radicals arise naturally in the atmosphere. The next step may be for scientists to figure out how to increase them.
Art credit: http://www.freeimages.co.uk
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