Reducing acid rain

The concept of long-range transboundary air pollution was born in the 1970s when scientists were able to link ecological damage to the deposition of acidifying pollutants that were transported long distances from their sources by prevailing winds. The solution to this complex problem required action locally, provincially, nationally and internationally.

Canada’s response

Canada created a federal-provincial team to devise a common solution ― the 1985 Eastern Canada Acid Rain Program. It established:

Canada also sought support from other countries with similar concerns, especially those in Northern Europe. This ultimately led Canada to join with European nations and the United States to sign the 1979 United Nations Economic Commission for Europe Convention on Long-Range Transboundary Air Pollution (UNECE LRTAP) and later sub-agreements on sulphur and nitrogen oxides.  The 1985 Protocol on the Reduction of Sulphur Emissions stipulates a national cap of 3.2 million tonnes of S02 to be met by the year 1993 onwards. In addition, a second regional cap of 1.75 million tonnes of SO2 is to be met in a Sulphur Oxide Management Area (SOMA) in southeastern Canada,  by 2000 onwards, as stipulated in the 1994 UNECE Protocol on Further Reductions of Sulphur Emissions. These international agreements allowed an exchange of scientific and technical knowledge and a coordinated approach to reducing acidifying pollution.

Fruitful negotiations with the United States led initially to joint scientific work and studies. A Memorandum of Intent between Canada and the United States concerning Transboundary Air Pollution was signed in 1980. It led to the 1991 Canada-United States Air Quality Agreement. The Agreement included specific commitments by both countries to:

The Agreement reiterated Canada’s commitment to cap SO2 emissions in the seven eastern provinces at 2.3 million tonnes by 1994 until 2000, and to cap national emissions at 3.2 million tonnes by 2000 onward. Under the Agreement, the United States put forward its program to cut its sulphur dioxide emissions from electric utilities by 10 million tons from 1980 levels by 2010 (about 50 percent). Since 1991, both countries have made substantial progress in reducing SO2 emissions. 

Ongoing scientific research, summarized in regularly updated science assessments, has continued to expand our understanding of acid rain and how the environment responds to our actions. The 1997 Acid Rain Assessment pointed to the urgent need for further sulphur dioxide reductions. It also showed a growing need to address the role of nitrogen oxides and the extent of ecosystem sensitivity to acidification. Stronger evidence pointed to possible forest and ecosystem damage at lower levels of pollution.

The result was the Canada-Wide Acid Rain Strategy for Post-2000, released by the Canadian Council of Ministers of the Environment in 1998, to help protect acid-sensitive areas and human health in Canada. It lays out a framework solve the acid rain problem in eastern Canada and prevent one in western and northern Canada. The main elements of the Strategy are:

In fulfilment of the commitment to further reduce SO2 emissions, Ontario, Quebec, New Brunswick and Nova Scotia announced a further halving of their provincial sulphur dioxide targets by 2010 to 2015. For its part, the United States is considering significant further sulphur and nitrogen oxide reductions for the coming 10 to 15 years. This would roughly match the further reductions announced in Eastern Canada.

Future actions

Environment Canada released its latest acid rain science assessment in 2004. It provides further impetus to address acid rain more fully based on today’s better understanding of the issue. It sets out:

Once again, the federal, provincial and territorial governments will work together with stakeholders and other partners to determine how best to protect forests, fish, birds, wildlife, agriculture, buildings and human health from damage due to acidification.

Related response instruments

A more specific list of instruments, in place for reducing the pollutants that contribute to acid rain include:

Related committees

There are several bodies involved with managing the acid rain issue, including:

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