The Environmental Protection Agency (EPA) is telling states to crack down on air pollution from plants during startup, shutdown and malfunction periods.

The regulation unveiled Friday rolls back exemptions that some states gave for decades to industrial facilities, allowing them to exceed pollution limits during the unusual stages without fines or other penalties.

{mosads}The EPA is formally telling 36 states to change their plans implementing air pollution standards in order to prohibit the spikes in emissions of substances like nitrogen oxides, sulfur dioxide and particulate matter.

“The called-for changes to state plans will provide necessary environmental protection and will give industry and the public more certainty about requirements that apply during these periods,” the agency said in a statement.

The move represents a victor for environmentalists, who long decried what they said was a major gap in the protections afforded under the Clean Air Act.

Greens say minority communities were disproportionately affected by the pollution, since they often live closest to manufacturers, fuel refiners and other industrial facilities.

“For too long, neighborhoods adjacent to dirty oil refineries, coal plants, and other sources of pollution have been left with little recourse to protect their families from toxic pollutants such as sulfur dioxide and soot,” Michael Brune, executive director of the Sierra Club, said in a statement applauding the Obama administration’s new rule.

“More often than not, the communities that face the worst of this pollution are low-income communities or communities of color,” he said.

The Sierra Club petitioned the EPA to make the change in 2011, arguing that the 36 states allowing the exemptions created an “affirmative defense” that is not allowed under the Clean Air Act.

The states with exemptions have until November 2016 to change them.