Canada - United States Air Quality Agreement Progress Report 2014: conclusion

Conclusion

Canada and the United States continue to successfully meet their commitments set forth in the 1991 Air Quality Agreement. While the initial focus of the AQA was on reducing emissions of SO₂ and NO_x, the major contributors to acid rain, the two countries expanded their efforts to cooperatively address transboundary issues such as groundlevel O₃ and PM. The Ozone Annex, added to the Agreement in 2000, committed both countries to reducing emissions of NO_x and VOCs, the precursors to ground-level ozone--a key component of smog. Considerable progress has been made to address transboundary O₃ pollution in the eastern border regions of each country.

In recent years, both countries undertook joint scientific and technical analyses to assess the transboundary transport of PM and precursor emissions to inform the consideration of whether to add an annex to the AQA in order to address PM. The results of these joint analyses are reported in the 2013 Transboundary Particulate Matter Science Assessment, the findings of which do not support adding a PM annex to the Agreement at this time. However, PM_2.5 remains a significant concern for both countries due to the potential risks to public health and ecosystems. The two countries will continue to monitor and evaluate PM_2.5, particularly in border areas, and will continue to develop and implement emission reduction programs to reduce PM_2.5 concentrations.

Both countries recognize that continued cooperative effort is necessary to address the ongoing health and environmental effects associated with acid rain and smog. The AQA provides a formal and flexible method for addressing transboundary air pollution and continues to provide a framework under which the two countries can cooperate on ongoing and future air quality issues.