Buried within the thousand or so pages of the mega-appropriations bill the Senate is expected to consider this week is a small but important amendment that could help keep the Northeast’s air from growing dirtier. In an era of environmental rollbacks, the Senate should support this measure.

The amendment holds up spending for the reworking of New Source Review, a critical part of the Clean Air Act that the Bush administration has concluded must be streamlined, until the nation’s most respected scientists have examined the changes. The NSR requires power plants and refineries to install improved pollution controls when they make substantial changes at their facilities that would result in increased air pollution.

The Environmental Protection Agency wants to relax these rules, making it easier to avoid the upgrades and increasing the likelihood the older coal-burning power plants, grandfathered under the 30-year-old act, will remain in service much longer. The administration denies that the new rules will result in more pollution and instead says it will spur more investment in new technologies for the old plants by making improvements easier.

The appropriations amendment, sponsored by Sen. John Edwards of North Carolina, delays the money for the rule changes until the National Academy of Sciences has an opportunity this year to offer its opinion on them. Its work, presumably, would be used to improve the rule changes, as the arguments from both sides of the issue are scrutinized. Such a study is important for the quality of the air that comes from these plants, which are mostly in the Midwest and mostly upwind of New England, and could be important for the many air-pollution issues Congress and the courts soon will face. Nine states, including Maine, for instance, recently sued the administration over the changes to New Source Review, saying they would damage the health of residents of these states. An NAS study could be important evidence in such a case.

Maine Sens. Susan Collins and Olympia Snowe, who both have excellent records on air pollution and have been fighting to strengthen current pollution rules, are expected to support the Edwards amendment. Given that Congress in the last 14 months has requested impact analyses from the EPA on the changes, requested an opportunity for public comment and requested an assessment of the changes on human health, and has been ignored each time, slowing the proposal now to let NAS scientists assess its effects is essential.

The Northeast has been suffering under the effects of dirty power plants from outside the region for years. New Source Review was supposed to slowly improve this situation as the plants were improved. To weaken these rules now is to condemn this region to decades more of unhealthy air. An NAS review would tell the public what to expect under the changes, and congressional representatives of this region can take the issue from there.