Arkansas must reduce its budgeted, or current allowable levels, of summertime nitrogen oxide emissions from power plants by 54 percent by 2017 under an update that the U.S. Environmental Protection Agency has proposed for its Cross-State Air Pollution Rule.
The proposal would decrease the allowable levels of emissions in 23 central and eastern states.
The Cross-State Air Pollution Rule was first finalized in 2011 and requires states to reduce power plant emissions that contribute to ground-level ozone and fine-particle pollution in other states.
As air travels, it can pollute the air in other states, causing those states -- through no control of their own -- to become out of compliance with federal air-quality laws.
Ground-level ozone is most hazardous during May through September, when warmer weather increases ozone levels. Health and environmental officials have tied ground-level ozone and nitrogen oxide emissions to respiratory illnesses, hospitalizations and deaths.
The EPA argues that nitrogen oxide regulations are effective in reducing regional movement of ozone. Additionally, emissions from tall stacks at power plants may disproportionately contribute to long-range movement of ozone pollution, the EPA says.
The proposed update to the rule is the third significant air regulation to come from the EPA this year. The first was the Clean Power Plan that targets carbon dioxide emissions at coal plants, and the second called for stricter ground-level ozone standards. State environmental officials said the latter is not expected to affect Arkansas.
The Clean Power Plan and ground-level ozone rules have been finalized, although Arkansas Attorney General Leslie Rutledge has joined in lawsuits to fight them.
Arkansas is already working with the EPA to reduce nitrogen oxide levels related to another air rule that passed in 1999 but has not yet been implemented in the state. The Regional Haze Rule calls for the reduction of nitrogen oxide and sulfur dioxide emissions that contribute to haze conditions at national wilderness areas.
In conjunction with plans to implement the Regional Haze Rule, Entergy Arkansas has proposed closing its White Bluff coal plant near Redfield, one of the state's biggest contributors to nitrogen oxide, sulfur dioxide and carbon dioxide emissions.
Arkansas' nitrogen oxide emissions travel northeast as far as Michigan and southwest through Arkansas to Texas, according to maps from the EPA.
Under the proposed update to the Cross-State Air Pollution Rule, Arkansas' allowable nitrogen oxide emissions during the summer would decrease from 15,110 tons in 2015 to 6,949 tons in 2017.
The EPA proposal involves 51 units at 22 electricity-generating plants in the state. Meanwhile, the state must also prepare a plan for reducing emissions.
Arkansas Department of Environmental Quality spokesman Katherine Benenati said the proposed update "substantially alters" the allowable-emissions picture in the state.
"We're still in the early phases of assessing impacts on the state," she wrote in an email.
Benenati couldn't quantify the exact amount of the state's current nitrogen oxide emissions in a given year but said the state is within its current 15,110-ton limit.
A spokesman for Entergy Arkansas said the utility would need some time to review the proposed update before making a statement on it.
The EPA proposal comes after a federal appeals court this summer upheld the agency's right to impose clean-air standards that block states from adding to air pollution in other localities. Some states and industry groups had argued that the rule was overly burdensome.
Under the EPA proposal, states would have to comply with air-quality standards for ground-level ozone, or smog, set by the George W. Bush administration in 2008. The current rules are based on pollution standards developed in the late 1990s.
The Cross-State Air Pollution Rule replaced the 2005 Clean Air Interstate Rule, which was the focus of a lawsuit that led a federal appeals court to direct the EPA to devise new rules on air traveling across states.
"This update will help protect the health and lives of millions of Americans by reducing exposure to ozone pollution, which is linked to serious public health effects including reduced lung function, asthma ... and early death from respiratory and cardiovascular causes," EPA Administrator Gina McCarthy said in a statement.
The EPA's proposed update on cross-state pollution would also affect power plant emissions in Alabama, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maryland, Michigan, Mississippi, Missouri, New Jersey, New York, North Carolina, Ohio, Oklahoma, Pennsylvania, Tennessee, Texas, Virginia, West Virginia and Wisconsin.
Under the proposed update, South Carolina and Florida, which are subject to the current rule, would be removed from the update because they don't contribute significant amounts of smog to other states.
The EPA said it will take public comments for at least two months before finalizing the rule next year.
Information for this article was contributed by Matthew Daly of The Associated Press.
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