Ozone Continues Decrease Over Northern Hemisphere

Ozone levels over the Northern Hemisphere have continued to decrease, the National Oceanic and Atmospheric Administration reported Wednesday.

But the report, “Northern Hemisphere Winter Summary,” predicted levels will recover “in the coming decades.”

Ozone is a form of oxygen that shields against harmful ultraviolet rays from the sun. The ozone destruction is caused by pollution from compounds containing chlorine or bromine.

Sam Oltmans, of NOAA’s Climate Monitoring and Diagnostics Laboratory in Boulder, Colo., said the report confirmed earlier studies.

Average ozone measurements for December 1995 through March 1996 were 10 percent to 25 percent lower than levels taken in the Northern Hemisphere during the same months in 1979 through 1986, the base period for such measurements.

Despite the continued decrease, NOAA predicted that ozone levels will recover if nations stick to agreements to restrict the use of chlorofluorocarbons and other compounds that harm the ozone layer.