Ozone in peril

CLOUDS of particles that accelerate the destruction of ozone have been found
near the Arctic Circle. Konrad Mauersberger of the Max Planck Institute for
Nuclear Physics in Heidelberg and his colleagues detected clouds rich in nitric
acid trihydrate (NAT) 20 kilometres above northern Sweden (Science, vol
290, p 1756). NAT particles speed up ozone depletion by generating chlorine
radicals from naturally occurring chlorine compounds.