Tue, Jul 13, 2004 - Page 6 News List

Scientists from six countries probing pollution's journey


A car pumps out exhaust fumes in Washington or New York, and five days later a hiker in Europes finds his or her lungs are hurting.

Scientists believe that polluting gases travel -- and that while crossing the Atlantic a reaction with sunlight turns them into ozone gas, which inflames the lungs.

In the biggest experiment ever on air pollution, 40 British scientists were heading for the Azores yesterday to test whether Europe is catching a good deal of damaging pollution from America, and even Asia, on the prevailing westerly winds. While the British scientists use research aircraft to measure the composition of the pollution in the jet stream (a fast current in the upper atmosphere) to Europe, scientists from the US, Canada, France, Germany and Portugal will do the same.

Alastair Lewis, from the University of York in northern England and head of the British expedi-tion, said: "We used to think air pollution was a local problem. Now we realize some pollutants, particularly ozone, are global. It is literally arriving here on the wind."

Some pollutant gases are short-lived; others form new pollutants as they mix and are subject to sunlight -- it is these changes scientists want to track.

Ozone, or lack of it, is better known because of the ozone-layer hole caused by chemicals such as chlorofluorocarbons reacting in the upper atmosphere and destroying the gas, which acts as a filter for sunlight and protects the skin from cancer.

However, in the lower atmosphere, ozone is dangerous. According to Lewis, when it reaches 40 parts per billion (ppb) in air it begins to damage plants and inhibit growth. If it reaches 100ppb it is regarded as dangerous to humans, inflaming the lungs and badly affecting old and vulnerable people.

"Background" ozone around the world has been increasing, thought to be caused by pollutants such as nitrogen oxides -- from car exhaust -- and volatile organic compounds, also emitted by vehicles and substances such as paint as well as natural sources. They react with sunlight to form ozone.

In the 1990s it was realized that ozone in the south of England rose dramatically in warm summers when there was an east wind, as pollution from Europe drifted cross the English Channel.

Now scientists see it as a world problem.

"Glog, it appears, is not the only global pollution problem," Lewis said.

The US is worried by ozone hitting its west coast due to pollution from Asia, especially China. On the other hand, it is believed US east-coast pollution moves north to Canada before being sucked upwards by weather fronts into the jet stream and is then deposited in Europe between three and five days later.

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