In fact, say the scientists, the ring of ozone that exists around the Tibetan plateau, which rises 4,000 metres above sea level and includes such famous peaks as Mount Everest and K2, is as concentrated as the ozone found in heavily polluted cities -- and may put climbers at risk. The findings are published in the journal Geophysical Research Letters.
"Around the circumference of Tibet, there's a halo of very high levels of ozone," said Professor G.W. Kent Moore, interim chair of the Department of Chemical and Physical Sciences at the University of Toronto at Mississauga and lead author of the study.
Study co-author John Semple, an associate professor of surgery and an avid mountaineer, was initially interested in how weather changes at high altitude can have a medical impact on climbers. Along with Moore, he examined earlier data and found several studies that alluded to higher ozone levels. Ozone is a highly reactive gas that can cause coughing, chest pain and damage to the lining of the lungs.
"In meteorology, it's a fairly well known phenomenon that when you get storms, quite often the tropopause -- which is the flexible boundary between the stratosphere and the troposphere -- descends," Moore says. "Its usual height might be 12 kilometres, and it might decend to nine or 10 kilometres. If you're on Mount Everest, you're eight or nine kilometres up. It might be that you're sometimes in the stratosphere."
The stratosphere is where most of the ozone that protects the globe from the sun's ultraviolet rays can be found;for this reason stratospheric ozone is often referred to as "good" as opposed to the ground-level ozone from pollution which is referred to as "bad". When the tropopause decends, the ozone descends with it. "Most people think about the mountains as one of the areas you
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Contact: Nicolle Wahl
nicolle.wahl@utoronto.ca
416-978-6974
University of Toronto
7-Dec-2005