However, acid rain continues to be a problem in eastern Canada. Reductions in lake acidity in other regions of Ontario, Quebec and Atlantic Canada have been modest, and some surface waters are continuing to acidify. In addition, there are concerns that the risks posed to forest health and productivity had been underestimated in the past, and that if nitrogen deposits continue at present levels, their contribution to acidification will eventually erode the benefits gained from reductions in SO2 emissions. Signed in October 1998, the Strategy provides the framework to address the continuing acid rain problem in eastern Canada, and to ensure that acid rain does not become a problem in other parts of the country. The Report indicates that work by Ministers is on schedule to complete the development of targets and timetables for emission reductions and to examine ways to address gaps in science and monitoring Nitrogen oxide emissions are being addressed through bilateral initiatives under the Canada-United States Air Quality Agreement,1991.
Nitrogen oxides contribute to both ground-level ozone and acid rain.
More specifically, Canada and the United States signed an agreement in April 1997 to develop a Joint Plan of Action on Transboundary Air Pollution, which led to the current negotiations for an Ozone Annex to the Canada-U.S. Air Quality Agreement, 1991. The Annex will reduce transboundary flows of nitrogen oxide emissions.