ABSTRACT
Canada and the United States share a set of ecosystems that span the North American continent and the transboundary nature of environmental problems creates the need for cooperation between the two countries at multiple levels. Ground-level, or tropospheric, ozone is a colourless and highly irritating gas that is produced when two air pollutants, nitrogen oxides and volatile organic compounds, react with each other in the presence of strong sunlight. The American and Canadian governments had first signalled their desire to jointly address the ground-level ozone problem three years before negotiations actually began. The federal government needed an effective interprovincial agreement to bring about ozone-related emission reductions within an accelerated timeframe, as it could not do so unilaterally. Air quality experts and officials were also interacting via the recently established North American Research Strategy on Tropospheric Ozone (NARSTO). NARSTO’s Ozone Assessment, carried out in the late 1990s, reviewed advances in the chemical, physical and meteorological science of ground-level ozone.
