Gov. Angus King should take pride in the simultaneous signing of petitions in eight states Thursday to require the Environmental Protection Agency to reduce pollution from out-of-state sources. The event was also a useful reminder of what can happen when states in this region cooperate.

Gov. King and Ned Sullivan, commissioner of the Department of Environmental Protection, worked for the last two years on the Ozone Transport Assessment Group (OTAG), to help gather data for the 36 participating states to meet current Clean Air Act standards. The group reported its findings in June, but left it to the EPA to decide specific reduction levels for nitrogen oxides. The King administration went a step further, urging states to petition for the toughest standards — including an 85 percent reduction in NOx for utilities — with the condition that all states in the group be required to meet the standard.

One reason Maine and the Northeast have trouble meeting the current EPA standards is that much of the pollution drifts in from other states, from as far away as 600 miles. Maine suffers most directly from dirty air in Boston and New York; Massachusetts gets it from New York and Pennsylvania; Pennsylvania is polluted from smoke stacks in Ohio. No state wants to be held to the more stringent pollution standard until its upwind neighbor is similarly charged, but some of the lowest-cost, dirtiest coal-burning plants in the nation are in the Midwest, where old pollution levels are grandfathered for many power plants. The issue is particularly important now because the EPA has proposed even tougher measures for the coming years. Those revisions include a reduction in the allowable ambient level of ozone, the primary component of smog.

EPA officials understood the Northeast’s predicament, but needed state cooperation to act. They got it Thursday, when Maine, New Hampshire, Vermont, Rhode Island, Connecticut, Massachusetts, New York and Pennsylvania urged action on cross-state pollution. In Congress, Maine Sens. Olympia Snowe and Susan Collins had previously tied their support of the revisions to the EPA removing the exemptions for some states and creating a level competition.

By cooperating, first by gathering the OTAG data and then by urging federal action, the Northeast states did together what each would have had trouble doing individually. Maine played an essential role in building a coalition for cleaner air, and its utilities should also benefit from fairer competition. Some would call it enlightened self-interest.