EPA curbs cross-state air pollution with new rule

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The US Environmental Protection Agency (EPA) finalized an update to the Clean Air Act's Cross-State Air Pollution Rule, also known as the Revised CSAPR Update, as the agency met a court-mandated deadline to change the rule. The long-awaited rule requires states to immediately reduce nitrogen oxide (NOx) emissions, the largest component of ground-evel ozone (or smog) that mostly comes from coal-fired power plants and is carried to downwind states.

The rule brings Northeastern states into compliance with the 2008 National Ambient Air Quality Standards (NAAQS) for ozone. Over one-third of coal plants in the Eastern U.S. have installed modern pollution controls for NOx. Those plants are not subject to the update.


A federal judge last year set a deadline of March 15 for the EPA to update its rule. This summer's emissions from power plants in the seven states, specified in a lawsuit that prompted the rule change, will help determine whether those states face additional regulatory requirements. The rule change follows years of legislation and litigation over states' environmental responsibilities to one another. The “Good Neighbor” provision in the Clean Air Act requires upwind states to consider emissions because it affects air quality in downwind states.

Power plants in 12 states (Illinois, Indiana, Kentucky, Louisiana, Maryland, Michigan, New Jersey, New York, Ohio, Pennsylvania, Virginia, and West Virginia) will now have to reduce NOx emissions by improving and upgrading NOx pollution controls, many of which have been in place. 22 downwind states are identified in the CSAPR, even though some states fall under both upwind and downwind categories.