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The state of the global ozone layer is usually observed through the network of ground ozone metric stations and satellite measuring systems. The total ozone layer is generally measured in Dobson units. The ozone layer depth, characterized as 300 Dobson units, is a 3-mm ozone layer under the pressure of 1 atmosphere. 340-360 Dobson units are considered a normal value. The intensive use of ozone depleting substances in the last 30 years has resulted in the global ozone depletion by 20 Dobson units.
As far as Tajikistan is a mountain country, the impact of harmful ultra-violet radiation here is essential. The elevation, local surface, atmosphere transparency, and other factors confine on enhance UV radiation. Mountain regions are especially exposed to the impact of UV radiation on human skin and eyes. For example in the Pamirs, the unprotected skin can burn in 10-15 minutes, as the altitude here exceeds 4,000 meters above sea level (the intensity of UV radiation increases by 40%), and the high angle of sun also raises the intensity of solar radiation. |
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Last update 03/03/2003 |
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The
thinnest ozone layer is observed during September-October over Antarctica. The ozone layer
here is so thin that the ozone hole is observed over the huge area of 25 million sq.km,
and the total contents of ozone does not exceed 220 Dobson units. Thus, there are
pessimistic trends of the expanding ozone hole proved by satellite TOMS measurements. 