EPA recognizes improvement in air quality in Rhinelander; entire state now meets the latest sulfur dioxide air quality standard

January 12, 2022

On Jan. 12, 2022, the U.S. Environmental Protection Agency (EPA) approved a request by the Wisconsin Department of Natural Resources (DNR) to redesignate the area around Rhinelander as “attainment” for the 2010 1-hour sulfur dioxide (SO₂) National Ambient Air Quality Standard (NAAQS). This designation officially recognizes that the air quality in the Rhinelander area is meeting this health-based air quality standard. The EPA’s announcement also means that all of Wisconsin is now meeting the 2010 SO₂ NAAQS.

Sulfur dioxide (SO₂) is an air pollutant regulated under both the federal Clean Air Act and Wisconsin state law. The largest source of SO₂ in the atmosphere is the burning of fossil fuels by power plants and other industrial facilities. Exposure to SO₂ can harm the human respiratory system and make breathing difficult. SO₂ emissions can also damage foliage and crops, form acid rain, and increase haze.

Based on monitored air quality data, a portion of Oneida County near Rhinelander was designated as nonattainment of the SO₂ NAAQS in 2013. Following this designation, Air Management worked closely with the Ahlstrom-Munksjö Rhinelander paper mill, the facility primarily responsible for SO₂ emissions in the area, to identify and implement new emissions control measures. As a result of these actions, monitored SO₂ concentrations decreased by over 75%, and the area’s air quality began meeting the NAAQS in 2018.

“Meeting the 2010 SO₂ NAAQS has been a complex process involving many areas of DNR’s Air Management Program, EPA and facilities in Wisconsin,” said Gail Good, the DNR’s Acting Environmental Management Division Administrator.  

The many actions taken to achieve this goal and include:

• attainment plan development
• revising facility operation conditions
• updating associated permits
• demonstrating attainment through stationary source modeling and operation of air quality monitors.

“This widespread improvement in SO₂ levels across the state is an air quality success story,” Good said “Emissions of SO₂ from Wisconsin sources are approximately 90% lower than 2002 levels, with most of this decline attributable to the use of cleaner-burning fuels at power plants and industrial facilities, along with the introduction of low-sulfur diesel fuels.”

Air News is published by the Wisconsin Department of Natural Resources, Air Management Program. Previous issues are available on the Air News webpage.