Why is "Air Quality Agreement" trending?

Wikipedia Overview

The Air Quality Agreement is an environmental treaty between Canada and the United States. It was signed on 13 March 1991 by Canadian prime minister Brian Mulroney and American President George H. W. Bush and entered into force immediately. It was popularly referred to during its negotiations as the "Acid Rain Treaty", especially in Canada. The treaty aimed at reducing toxic air pollutants primarily responsible for causing acid rain, such as sulfur dioxide and nitrogen oxide. Negotiations began in 1986 when Mulroney first discussed the issue with then-president Reagan. Mulroney repeatedly pressed the issue in public meetings with Reagan in 1987 and 1988The Government of the United States of America and the Government of Canada, hereinafter referred to as "the Parties",
Convinced that transboundary air pollution can cause significant harm to natural resources of vital environmental, cultural and economic importance, and to human health in both countries;
Desiring that emissions of air pollutants from sources within their countries not result in significant transboundary air pollution;
Convinced that transboundary air pollution can effectively be reduced through cooperative or coordinated action providing for controlling emissions of air pollutants in both countries;
Recalling the efforts they have made to control air pollution and the improved air quality that has resulted from such efforts in both countries;
Intending to address air-related issues of a global nature, such as climate change and stratospheric ozone depletion, in other fora;
Reaffirming Principle 21 of the Stockholm Declaration, which provides that "States have, in accordance with the Charter of the United Nations and the principles of international law, the sovereign right to exploit their own resources pursuant to their own environmental policies, and the responsibility to ensure that activities within their jurisdiction or control do not cause damage to the environment of other States or of areas beyond the limits of national jurisdiction";

Noting their tradition of environmental cooperation as reflected in the Boundary Waters Treaty of 1909, the Trail Smelter Arbitration of 1941, the Great Lakes Water Quality Agreement of 1978, as amended, the Memorandum of Intent Concerning Transboundary Air Pollution of 1980, the 1986 Joint Report of the Special Envoys on Acid Rain, as well as the ECE Convention on Long-Range Transboundary Air Pollution of 1979;

Convinced that a healthy environment is essential to assure the well-being of present and future generations in Canada and the United States, as well as of the global community;
Have agreed as follows: ...