Industries contribute air pollution in the form of smog and haze in "downwind states".

Sometimes pollution from "upwind states" blows into the downwind states, which can affect their air quality standards.

Air emissions in these states contribute to unhealthy levels of ground-level ozone, fine particles or both in downwind states.

"We're going to continue to look at how to provide the relief to downwind states."

Given the Bush administration's failure of environmental leadership, states must limit mercury emissions to protect their own residents as well as downwind states.

Their toxic brew is carried aloft and deposited in Vermont and other downwind states.

If Connecticut is going to rely on the upwind states to cut their emissions, he said, it must "do something for the downwind states."

The Clean Air Act's "good neighbor provisions" require states to eliminate emissions that substantially contribute to dirty air in downwind states.

For downwind states like Vermont that have taken firm steps to responsibly reduce air and water pollution, cross-state pollution has long been a particularly destructive and frustrating obstacle.

All pollutants drift across state lines with the wind, but smog - or, more properly, ozone - is a particular problem for downwind states.