New York and Connecticut are suing the Ohio-based utility AEP, accusing it of producing excessive pollution from 10 coal-fired plants.

The suit, filed in the US District Court for the Southern District of Ohio, accuses AEP of modifying older power plants without performing the environmental reviews and pollution-control upgrades required by law. The suit contends that winds carried pollutants 500 miles from AEP’s plants in the mid-West to New York and Connecticut.