The level of regulated air pollutants in Arkansas continued to decline throughout 2016, the latest year for which data are available, according to a report from the Arkansas Department of Environmental Quality.
The "2017 State of the Air" report assessed ground-level ozone concentrations and concentrations of other pollutants regulated by the National Ambient Air Quality Standards program.
The report, which can be found at arkansasonline.com/ozone, noted declines from 2005 to 2016 where the state has monitors in ground-level ozone, particulate matter 2.5 and 10, carbon monoxide, nitrogen oxide, sulfur dioxide, and lead. Arkansas is one of only 12 states that meets all federal air quality standards, although it was not meeting ozone standards a few years ago.
Since 2005, the state has seen a few blips upward in emissions. The state showed an increase between those years in sulfur dioxide concentrations measured in Pulaski County, although they were still well below the national standards' maximum.
[DOCUMENT: Read the 2017 State of the Air report]
Many of the air pollutants, such as lead and carbon monoxide, are at levels so far below the limit that the department hasn't been concerned about them "in a while," according to Tricia Treece, a supervisor in the Air Quality Division.
Stuart Spencer, an associate director in the department who leads the Office of Air Quality, said in April during an Arkansas Pollution Control and Ecology Commission meeting that he believed the downward trend of certain air pollutants was attributable to both regulatory and nonregulatory efforts.
Facilities trading emissions credits through the Cross-State Air Pollution Rule has helped reduce pollutants, Spencer said.
The Arkansas chapter of the Sierra Club said in a statement that air quality improvements also can be attributed to less use of coal-fired power plants. Coal plants have been surpassed nationwide by natural-gas plants, which emit fewer pollutants.
"Coal-burning plants spew millions of tons of pollutants into our air each year, contributing to unsafe levels of ozone and sulfur dioxide," chapter Director Glen Hooks said in the statement. "Our state's air quality will improve dramatically once we finally retire Entergy's White Bluff and Independence coal plants -- two giant facilities that lack modern pollution controls and are annually among the largest sulfur dioxide emitters in the nation."
Hooks noted utilities' increasing investment in solar and wind power as a sign that the electricity sector is changing in more ways than just a pivot to natural gas.
The Sierra Club favored sulfur dioxide emissions-controlling scrubbers for the White Bluff and Independence coal plants, but in March the U.S. Environmental Protection Agency approved Arkansas' recently submitted plan to reduce those emissions and regional haze through Cross-State Air Pollution Rule trading.
Treece said the trading would reduce the total sulfur dioxide emissions in the state at a lower expense to those coal plants. Entergy estimated the scrubbers' cost at about $2 billion total.
"EPA did technical modeling and found that program as a whole provided more visibility [haze] impacts than source targeting," Treece said.
The Sierra Club argued that trading would not as significantly reduce sulfur dioxide emissions from individual plants, such as the White Bluff and Independence plants, which may be able to buy credits to emit more.
In various air quality planning documents, the EPA notes that sulfur dioxide and the fine particles that can form in sulfur dioxide's interaction with surrounding air have been linked to "increased respiratory illness, decreased lung function, and even premature death."
Nitrogen oxide contributes to ground-level ozone, which can be hazardous to health at certain levels.
Metro on 05/06/2018