Maine’s decision on whether to go along with a compromise on clean-air standards for the Midwest or to stick to its earlier demands that power plants there clean up to the same extent as the Northeast is simple. It should reject any compromise at least until it has been assured that the Midwest power plants will comply with an agreement.

The question arises because of a couple of court setbacks for the Environmental Protection Agency, which had taken the Northeast’s position that exempted power plants in the Midwest should by 2003 meet the standard of .15 pounds of nitrogen oxides per million Btu as required in New England. Many plants in the Midwest emit NOx at more than triple that level. In rejecting the EPA’s attempt to require the plants to stop producing pollutants, which form ozone and drift eastward, the courts cited the agency’s lack of convincing evidence that such rules are necessary.

But they are clearly necessary if the Northeast is going to comply with federal regulations within the Clean Air Act. Maine, which has had one of its hottest summers on record, has had only a few high ozone days, and most of those occurred recently during days with more moderate temperatures. The reason? Prevailing winds for much of the summer have sent air from the west, Vermont and New Hampshire. When it shifted to the Southwest in recent weeks, Maine’s air quality worsened, according to the Department of Environmental Protection, even during times of lower temperature.

Gov. Angus King spelled out his desire in a New York Times commentary last week. The piece, written with his former commissioner of the Department of Environmental Protection, Ned Sullivan, called on Congress to level the playing field, requiring all sources east of the Mississippi River that are contributing to the regional ozone problem to reduce their emissions. Congress should also impose the same tough emission standards on old coal-fired power plants that the new generation of cleaner-burning electric plants must meet.

Congress should, but it won’t do any such thing. As long as it can pass a dispute among regions back to the federal agency, it will. So the question remains, will Maine go along with a compromise standard or press its case, possibly by suing. The compromise is substantial — it would bring the Midwest to .20 pounds per million Btu by 2005 — but has several problems with it. Most importantly, not all Midwestern states have agreed to it and there has yet to emerge a way to enforce it.

Gov. King said he is unwilling to sign on to a compromise until both the Midwestern states and the power plant owners there agree to it. That’s the correct course. Maine gains no advantage in agreeing early to a compromise measure and doing so precludes it from negotiating tougher standards later. In addition, the delay gives the EPA time to defend itself again in court.

Whatever the politics of this debate — and with two dozen states and coal and power-company lobbyists, there’s politics aplenty — the basic issue remains one of fairness. The Northeast began this fight demanding that the Midwest meet the same air-pollution standards it meets so residents in this region can breathe cleaner air.

That’s a fight worth continuing.