51动漫

THANKS to cleaner air, London鈥檚 old buildings are not disintegrating as fast
as they were. For the past 20 years, Stephen Trudgill of Cambridge University
and his colleagues have been measuring the loss of stone from St Paul鈥檚
Cathedral caused by acid rain. The average rate has halved in the past 10 years,
from 45 micrometres a year to just 24, they will report at a conference next
week. The closure of Battersea power station in 1983 helped to halve levels of
sulphur dioxide. 鈥淚t鈥檚 encouraging, but there鈥檚 no room for complacency,鈥� warns
Trudgill.