While the existing "New Source Review" regulations and the Clear Skies proposal both call for reducing emissions of mercury, nitrogen oxides and sulfur dioxide, the difference lies in implementation. The current system relies on public advocates to engage utilities in lengthy legal battles to reduce emissions. Meanwhile, Clear Skies calls for the institution of a "cap-and-trade" system whereby utilities could buy and sell the right to generate limited amounts of pollution. While Bush administration environmental officials say a similar cap-and-trade system successfully mitigated acid rain during the 1990s, critics point out Clear Skies would allow major utilities to actually increase emissions if they were willing to buy credits from those polluters willing to cut back. That could lead to more mercury releases in some areas, which concerns observers since the heavy metal is such a potent toxin.
The National Academy’s report was released just as Congress began debating passage of Clear Skies. If implemented, the new regulations would replace the existing New Source Review system, which first went into effect in 1977 as part of the Clean Air Act.