Acid Rain and Pollution Without Borders

Pollution does not stop at national borders. In the 1960s Swedish scientists linked acidified lakes and dying fish to sulphur emissions from industry in Britain and Central Europe, carried hundreds of kilometres by the wind. Sweden raised the issue at the 1972 UN Conference on the Human Environment in Stockholm. In 1979 European and North American countries signed the Convention on Long-range Transboundary Air Pollution, the first international legally binding agreement on air pollution with a broad regional scope.

The United States and Canada later signed an Air Quality Agreement in 1991. An earlier case, the Trail Smelter arbitration between the US and Canada, concluded in 1941, established that a state should not allow its territory to cause serious environmental harm to another. Reductions in sulphur emissions since then show that international cooperation on pollution can work, though new problems continue to arise.