Chemical coolants used in refrigerators and automobile air conditioners contribute to ozone depletion by a small but measurable amount, says a new NASA study.
The researchers estimated that the common chemical coolants. known as hydro fluorocarbons, (HFCs) will cause a 0.035% decrease in ozone by 2050.
The ozone layer comprises a belt of ozone molecules located primarily in the lower stratosphere-- responsible for absorbing most of the sun's harmful UV rays before it reaches Earth's surface.
"We are not suggesting HFCs are an existential threat to the ozone layer or to ozone hole recovery, but the impact is not zero as has been claimed," said Margaret Hurwitz, atmospheric scientist at NASA's Goddard Space Flight Centre in Greenbelt, Maryland.
The study, which focused on the five types of HFCs expected to contribute the most to global warming by 2050, found that the gases indirectly contribute to ozone depletion.
Findings showed HFC emissions cause increased warming of the stratosphere, speeding up chemical reactions that destroy ozone molecules. They also decrease ozone levels in the tropics by accelerating movement of ozone-poor air.
HFCs have been adopted as replacements for chlorofluorocarbons (CFC) and hydro chlorofluorocarbons (HCFC) in refrigerators and air conditioners.
"HFCs are, in fact, weak ozone-depleting substances," Hurwitz noted.
But the scientists also found HFCs have linear impact on stratospheric temperature and ozone change. Such a direct relationship will prove useful for evaluating the impacts of emerging HFCs, Hurwitz said.
It is believed that HFC emissions by 50% would decrease the ozone change by a comparable amount.
"We can provide policy makers with an estimate of the stratospheric impacts of new HFC gases," Hurwitz noted.
Projections show that by 2050, the amount of global warming by all HFCs could be as large as 20% that of carbon dioxide, the study pointed out.
The findings appeared in the journal Geophysical Research Letters.
