Atmos. Chem. Phys. 9, 7737–7751 (2009)

Earth's natural sunscreen — the stratospheric ozone layer — has thinned during the past few decades because of the rise in atmospheric pollutants such as chlorofluorocarbons. This has allowed more ultraviolet (UV) radiation to reach many parts of the planet's surface since the 1970s. However, other forms of pollution have helped to shield Earth from UV rays.

Using an atmospheric radiation model, Gunnar Myhre of the University of Oslo and his colleagues found that, since 1750, pollutants such as sulphate, soot particles, sulphur dioxide and nitrogen dioxide have reduced the amount of UV light reaching some industrialized regions by as much as 20%. By scattering or absorbing UV light, such pollution may be masking some of the effects of ozone depletion, the authors say.