FPL, owner of the Wyman Station power plant in Yarmouth, needs to reduce the plant’s emissions of nitrogen oxides, which contributes to smog. For nearly a year, the Natural Resources Council of Maine has been trying to get the public interested in this question before the Board of Environmental Protection: Should FPL be required to reduce the pollutant directly at the plant or could it make some upgrades and also purchase pollution credits from nearby plants to offset its own emissions?

Not surprisingly, except for those directly affected by plant emissions, the question has not had the captivating power of, say, the rat-eating episode of “Survivor,” but there is a good reason for this. Either method of pollution reduction yields benefits to the public -although in slightly different ways – so the issue seemed less an environmental battle than an exercise suited for policy wonk summer camp. Then Gov. King, normally as nimble as they come, handed the NRCM a fight.

In favoring the plant-specific NOx cuts, the governor said last week in rebuttals to the environmental group, NRCM’s “facts were wrong, their science was wrong and their policy was wrong.” The governor may have felt compelled to act because the BEP in an initial decision in June sided with the plant-specific cuts, or maybe he just didn’t like the NRCM’s recent press conferences on the issue. Whichever, his comments got the environmentalists bigger headlines than they could have gotten on its own.

It is understandable, however, that the governor would prefer the method that also allows for the purchase of credits. On balance, trading credits keeps Maine part of a regional strategy to cut air pollution, rather than trying to do the entirely on its own. It is also quite a lot cheaper. FPL estimates that the cost of reducing the necessary 1,500 tons of NOx annually at $50 million; making a two-thirds cut toward that maximum emission level at the plant and trading credits for the final third would cost $10 million plus, currently, credits at $600 per ton. Cost savings, though, isn’t the only or even the primary reason for preferring the second method.

Ozone, a component of smog, doesn’t form the minute NOx leaves a smokestack. It takes three or four hours, depending on the amount of sunlight and other conditions, according to the Department of Environmental Protection. Drifting Northeast during that time, the pollution ends up affecting not the neighbors around the plant but people miles away. Maine’s location places it downwind of neighboring states with major power plants. If the possibility of credit trading causes them to reduce emissions or to act on new upgrades based on the market for credits, Maine reaps a benefit.

That’s why the Ozone Transport Region, made up of states from Maine to Virginia, favors trading credits. Maine has been an enthusiastic member of the OTR for good reason. Air-pollution problems are most effectively addressed not simply within a state’s boundaries but regionally. This holds true for NOx. Sticking with the OTR has helped Maine have more influence in Washington and has provided other benefits, such as air-pollution tracking that Massachusetts did for the Northeast that Maine did not have the equipment to do itself.

There’s no compelling reason for Maine to leave the OTR on this issue and several good reasons it should stay. Of course, Maine plants must do their part, but the BEP should make its final decision, due next month, on the most effective outcomes in Maine, but not necessarily from Maine. Those in doubt can contact the governor.