Reducing acid rain

One of the primary causes of acid rain is emissions of sulphur dioxide (SO2) from power stations and other large combustion plants.

In 1985, twenty-one countries signed the Helsinki Protocol to reduce their emissions of SO2 to not more than 70% of their 1980 levels by 1993. According to the 1994 Progress Report on the US-Canada Air Quality Agreement, both countries have pledged to reduce their SO2 emissions at 40% below 1980 levels by the year 2000. The USA is expected to begin SO2 emission reductions in 1995.