Winds of change: reducing transboundary air pollutants.
Sulfur dioxide, nitrogen oxides, volatile organic compounds, persistent organic pollutants, particulate matter, and heavy metals---air pollutants once thought to be problems that could be solved locally, where the effects occur---are all currently being discussed in international forums. A spate of meetings and agreements in recent months has shown many international governments to be more willing than ever to try to limit the amount of their air pollution that drifts into other countries. Prompting this policy shift are increasing emissions in some parts of the world, better monitoring, and an improved understanding of air pollution transport and the effects of air pollution. In most regions of the world, however, no international agreements on air pollution exist at all, while in others, many overlapping local, multilateral, and global agreements address the problem simultaneously. According to the World Health Organization, air pollution causes nearly 3 million deaths per year, and the U.S. Environmental Protection Agency estimates that ground-level ozone causes damage to U.S. crops totaling $1-2 billion each year.