Wisconsin’s 2019 Air Quality Success Faces Challenges

Don Behm and Jon HeinrichWI Green Fire, November 5, 2019

Milw highways

Most Wisconsin residents can breathe easy: fully 94 percent of the population lives in areas meeting federal air quality standards.
That is the good news within the state’s 2019 Air Quality Trends Report that found continuing improvement as concentrations of several pollutants decreased throughout the state.

The Wisconsin Department of Natural Resources’ report is based on more than 15 years of state monitoring data, through 2018, for key pollutants that impact public health. The improvement in air quality can be linked directly to implementation of federal and state pollution control efforts, according to the WDNR’s Air Program.

The report is available at the department’s air quality web page: https://dnr.wi.gov/topic/AirQuality/Trends.html.
Wisconsin residents benefit from the good air quality that has been achieved. Unfortunately recent actions by the Trump administration and the U.S. Environmental Protection Agency threaten Wisconsin’s progress and introduce obstacles to addressing critical air quality issues such as climate change and air toxics emissions. Federal actions taken or proposed include:

  • Removal of a summertime ban on E15 (gasoline with 15% ethanol) use. Ethanol contributes to ground level ozone formation in warm weather.
  • Proposals to weaken the fuel economy standards for cars and light trucks set by the Obama administration and to eliminate the longstanding ability of California to set more stringent requirements, which has benefited Wisconsin and other states.
  • Elimination of rules and reporting requirements for methane emissions, and a halt to enforcement of a rule that prohibited the use of hydrofluorocarbons in air-conditioners and refrigerators, both greenhouse gas contributors.
  • Proposals to weaken an Obama administration rule limiting mercury emissions from coal-fired power plants, setting the stage for reduced control of other air toxic emissions. In Wisconsin, the issue of mercury contamination is critically important because of our many lakes, rivers, streams and wetlands and numbers of people who catch and eat fish. Mercury air emissions are responsible for methyl mercury contamination of fish. Methyl mercury is a human toxin.

These federal actions threaten to erase the significant achievements highlighted in the WDNR air quality trends report. The successes highlighted in the report include reductions in fine particles, ozone, and sulfur dioxide emissions. However, progress is at risk as discussed below.

Fine Particles
All of Wisconsin is in attainment of federal standards for fine particles suspended in the air following a 35 percent decrease statewide in those concentrations since 2002. That includes southeastern Wisconsin where air quality is 40 percent below the federal standard for fine particles though the region was in violation just a decade ago.

Sources include forest fires, wood stoves, and emissions of precursor pollutants — such as nitrogen oxides and sulfur oxides from power plants, industries and automobiles — that react in the atmosphere to form the fine particles.

But this ongoing success could be jeopardized if the state relaxes its guard and believes the job is done. Nationwide, an equal decline in fine particle pollution over the past few decades has been reversed in just a few years, according to researchers at Carnegie Mellon University.

Federal data show a 5.5 percent increase on average in fine particle pollution across the U.S. between 2016 and 2018, the researchers reported in October. Possible contributors include an increase in total miles driven in automobiles, a decrease in enforcement of the federal Clean Air Act, and wildfires in western states.

Inhaling fine particles poses a significant risk to public health because they penetrate deep into the lungs and can enter the bloodstream, according to the WDNR report. Studies have linked exposure to fine particles to premature death from heart or lung disease, as well as asthma and airway irritation.

There has been a 50 percent drop in emissions since 2002 of pollutants that form ozone at ground level. Those precursor pollutants include nitrogen oxides and volatile organic compounds (VOC) that react when they meet in the lower atmosphere on hot, sunny days to form ozone. The chemicals are emitted from cars, power plants, chemical plants, refineries and other industries.

This success story, particularly in southeastern Wisconsin, could slip away following relaxation of past practices.

In 2018, the U.S. Environmental Protection Agency designated only the eastern portions of six counties along the Lake Michigan shoreline from the state line north to Door County as nonattainment for ozone. Previously, full counties were considered either in or out of compliance. Also last year, one other shoreline county, Racine, was declared fully in compliance.

That opens the door to less stringent emission limits for the manufacturing plant being built in Racine County by the Foxconn Technology Group and raises the concern that increased emissions of ozone-forming chemicals there will impact the ability of nearby non-attainment areas to achieve compliance.

On other fronts, the Trump administration is planning to block higher vehicle fuel efficiency standards – burning less fuel would release fewer pollutants per mile – set by the Obama administration. At this time, the Trump administration is fighting California in the courts to take away that state’s authority to set more stringent tailpipe emission limits than the federal standard.

A steady tightening of emission limits and ratcheting up of fuel efficiency standards in the past played a significant role in improving Wisconsin’s air quality.

Federal and California tailpipe standards limit exhaust emissions of five pollutants: hydrocarbons, nitrogen oxides (NOx), carbon monoxide, particulate matter (for diesel vehicles only), and formaldehyde. Hydrocarbons and NOx are the major contributors to ground level ozone.

Transportation has ascended to the largest source of greenhouse gas emissions in the United States (U.S. Energy Information Administration, December 2017). The tailpipe standards established by the Obama administration, including 54.5 miles per gallon across sales by 2025, focused on limiting carbon dioxide emissions and provided several ways for manufacturers to achieve compliance. The Trump administration proposal would hold average fuel economy to 37 miles per gallon after 2020. California is proposing 51 miles per gallon to be achieved by 2026 and they have received support from four major manufacturers – Volkswagen, Ford, BMW, and Honda.

Public health is at risk if limits on emissions of ozone precursors from automobiles and manufacturers become less stringent. Exposure to ozone causes chest pain, coughing, throat and airway inflammation, and reduces lung function, according to the air quality trends report. Ozone pollution exacerbates bronchitis, emphysema and asthma.

Sulfur Dioxide

Sulfur dioxide emissions have dropped 89 percent since 2002 from power plants, paper mills and other industries that burn fossil fuels.

In 2013, the U.S. Environmental Protection Agency designated a portion of Oneida County encompassing the City of Rhinelander and four towns as nonattainment for sulfur dioxide. Following the implementation of an attainment plan, concentrations of the pollutant in the air have declined and currently meet the federal standard, according to the WDNR report.

Exposure to sulfur dioxide can constrict airways in the lungs and result in coughing and shortness of breath, as well as increased asthma symptoms, the air quality trends report said.


Don Behm,Wisconsin’s Green Fire (WGF) communications team, is a retired reporter for the Milwaukee Journal Sentinel

Jon Heinrich, WGF Air Quality Work Group chair, is retired form the WDNR air program



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