Researchers say the Earth's atmosphere is losing its ability to remove air pollutants.
The decrease in the amount of just one molecule may lead to an increase in the number of greenhouse gases remaining in the air.
Climatologists found fewer hydroxyl radicals in the atmosphere than they expected, according to a report in the journal Science.
Over the past 22 years concentrations have decreased by around 10% worldwide.
Scientists had trouble making the estimate since hydroxyl radicals exist for only one second before changing into something else.
Ronald Prinn, of the Massachusetts Institute of Technology which led the study, said: "This one molecule is very, very important. It is the critical cleaning chemical for the atmosphere."
Original source of this article: Ananova
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