The debate over the details of the Clean Air Act rages on in the political arenas of the country, but one rule change that was finalized recently aims to protect states from being polluted by their neighbors.
The Cross-State Air Pollution Rule (CSAPR) will have states that create the majority of pollution in the country tighten their air quality standards to prevent neighboring states from being negatively effected by the emissions. This rule applies heavily to those states with a high number of coal-based power plants, and was one of the points of contention between those who claim changing air regulations will hurt the economy and those who are backing the laws.
One way to help understand the rule is to look at it as if it's a large-scale version of many of the smoking laws passed in the past few years. The CSAPR is an attempt to keep some states from hurting others with their large-scale secondhand smoke.
This new law doesn't go into effect until 2012, so if you want to improve the quality of air you breathe now, invest in an air purifier to leave your home or office full of fresh, clean air.