The 1991 Canada US Air Quality Agreement was the result of years of negotiations between Canada and the United States to reduce air pollution on both sides of the border. The agreement aimed to address the growing concern over pollution caused by industrial activities, transportation and other human activities, which were causing significant harm to human health and the environment.

The agreement established a framework for cooperation between the two countries to reduce emissions of pollutants, including particulate matter, sulfur dioxide, nitrogen oxides, volatile organic compounds and acid rain. The agreement set ambitious targets for the reduction of these pollutants, with a particular focus on sulfur dioxide and nitrogen oxides.

Under the agreement, both countries pledged to reduce sulfur dioxide emissions by 50% and nitrogen oxide emissions by 30% by the year 2000. The agreement also established a system for monitoring and reporting progress towards these targets, as well as a dispute resolution mechanism to resolve any conflicts that may arise.

One of the key successes of the agreement was the establishment of the Canada-US Acid Rain Program, which aimed to reduce acid rain caused by emissions of sulfur dioxide and nitrogen oxides. The program was implemented in 1994 and resulted in significant reductions in acid rain, with sulfur dioxide emissions declining by 30% and nitrogen oxide emissions by 15% between 1990 and 2010.

The success of the 1991 Canada-US Air Quality Agreement has been attributed to the strong cooperation between the two countries, as well as the commitment by both governments to address the issue of air pollution. The agreement has provided a model for other countries seeking to reduce air pollution and has contributed to the broader global effort to address climate change.

Overall, the 1991 Canada-US Air Quality Agreement was a significant achievement and has had a lasting impact on air quality in both countries. The agreement continues to serve as a reminder of the importance of cooperation and collaboration in addressing environmental challenges.