An inversion layer hangs over the residents of Boulder, Colorado. Click on image for full size (147 Kb) Source: T. Eastburn

The air is shared among all living things. When it is polluted by a factory in Asia, a fire in Australia, a dust storm in Africa, or car emissions in North America, the sharing continues despite the fact that these chemicals and particles have detrimental effects.

Scientists have determined many of the harmful local effects of air pollution. We know, for instance, that air pollution can negatively impact human health and cause coughs, burning eyes, breathing problems, and even death. We know that atmospheric haze or smog reduces visibility and that acid rain from chemical emissions damages property, pollutes water resources, and can harm forests, wildlife, and agriculture.

But what are the regional and global impacts of air pollution? Through large scientific field campaigns such as MILAGRO, scientists are beginning to track its movement from cities into regional and global environments. Their goal is to determine air pollution’s movement and impact on climate and atmospheric composition locally, regionally, and globally.

Is human-produced air pollution and its effects an example of the "Tragedy of the Commons" –– a concept that states that any resource open to everyone will eventually be destroyed? Despite the fact that people are creating much of today’s air pollution, the answer will ultimately depend on how humankind responds to the problem. A lot has been done to improve air quality in recent decades, but we still have a long way to go.