Ozone Nonattainment Areas

The U.S. Environmental Protection Agency (EPA) has designated 10 counties in eastern Wisconsin as nonattainment areas for the eight-hour National Ambient Air Quality Standard for ozone. This means that these counties have recorded ozone levels exceeding the federal air quality standards during 8-hour periods.

Ozone Nonattainment History
Current Nonattainment Designations and Maps
Current Design Values
2007 Nonattainment Area Redesignation Request

Ozone Nonattainment History

Over the past several decades, citizens in eastern Wisconsin have been suffering from exposure to unacceptable levels of ozone. EPA designated nonattainment areas in southeastern Wisconsin shortly after developing the first ozone standard in 1979. As the ozone monitoring network grew and measured unacceptable ozone concentrations in other locations, additional counties along the Lake Michigan shoreline were added to the list of nonattainment counties.

In 1997, EPA revised the ozone standard, replacing the previous 1-hour standard with the current 8-hour standard (meaning that ozone levels are averaged over an 8-hour period). In April 2004, EPA designated 10 counties in Wisconsin as nonattainment areas for the 8-hour standard.

Current Nonattainment Designations and Maps

Currently, 10 Wisconsin counties do not meet the federal government's 8-hour standard for ground-level ozone. The counties, shown on the map below, are Door, Kewaunee, Manitowoc, Sheboygan, Washington, Ozaukee, Waukesha, Milwaukee, Racine and Kenosha counties.

Current Design Values

Design values are averages of the ozone levels recorded at each air quality monitoring site. the design value is the average over a three-consecutive-year period of the fourth-highest ozone concentrations at a given site during each of those three years. This average is then compared to the 0.08 parts per million (ppm) federal standard for ozone. If the design value is greater than 0.08 ppm, the area around the monitoring site is in violation of ozone standards and EPA designates the area as nonattainment.

The DNR has compiled a state map showing the current ozone design values in Wisconsinn On this map, numbers higher than 84 represent a violation of the 0.08 ppm ozone standard between 2004 and 2006. Two monitoring locations--Newport in Door County and Sheboygan in Sheboygan County--exceeded the standard with design values of 86. Values elsewhere in the state ranged from 65 at the Popple River along the border with Michigan's Upper Peninsula to 83 in Chiwaukee Prairie, near the Illinois border in Kenosha county. In general, the highest values were in the eastern part of the state, along Lake Michigan.

You can view an image of the map in a separate window by clicking the thumbnail image at the right or download a PDF version [PDF 89KB].

2007 Nonattainment Area Redesignation Request

Based upon air quality monitoring data, the DNR submitted a request to the U.S. EPA on June 14, 2007, to redesignate eight counties in eastern Wisconsin from nonattainment to attainment of the 8-hour ozone NAAQS. The requests for redesignation were two separate requests – the basic nonattainment areas (Kewaunee and Manitowoc counties) and moderate nonattainment area (Kenosha, Milwaukee, Ozaukee, Racine, Washington and Waukesha counties). The proposed requests are below. Public hearings were held in April 2007, and the public comment period ended May 7.

Below are links to Web pages containing links to documents submitted to EPA.

For more information on the redesignation requests, contact Al Shea at 608.266.5896 or by e-mail.

Redesignation submission for Milwaukee 6-county area
Redesignation submission for Manitowoc and Kewaunee counties

Frequently Asked Questions About Redesignation

The following are frequently asked questions with answers regarding the DNR’s request that the U.S. EPA redesignate eight counties in eastern Wisconsin from nonattainment to attainment status for ozone because of improved air quality in the region.

• Why did the DNR make an ozone redesignation request?
• What did the DNR do to request ozone attainment?
• What happens if USEPA approves the redesignation request?
• What is the timeline for the redesignation request?
• What happens to existing emission control programs in the eight counties?

Why did the DNR make an ozone redesignation request?

Eight of the 10 counties in eastern Wisconsin that were identified in 2004 as violating the federal air quality standard for ozone now meet the standard based on 2004–2006 monitoring data. The eight counties are Kenosha, Kewaunee, Manitowoc, Milwaukee, Ozaukee, Racine, Washington and Waukesha. Door and Sheboygan counties continue to record violations of the ozone standard. In January 2007, Governor Doyle directed the DNR to request ozone attainment redesignation for the eight-county region.

What did the DNR do to request ozone attainment?

The DNR developed a request to U.S. EPA demonstrating that the eight counties are meeting the standard and asking that EPA approve the request. The request included a maintenance plan that demonstrates that emission reductions will continue 10 years into the future. The maintenance plan also includes contingency measures to control emissions if the area’s air quality violates the ozone standard in the future.

What happens if U.S. EPA approves the redesignation request?

If approved, the requirements for permitting business expansions in the eight counties would change. The emission threshold that triggers a permit for new sources (called New Source Review) would be increased, resulting in fewer sources reaching the threshold and needing permits. No emissions offsets (reductions equal to the additional emissions being proposed) would be required for major new sources or major modifications.

What is the timeline for the redesignation request?

The DNR submitted the redesignation request to U.S. EPA in June 2007. U.S. EPA could take up to 14 months to review the request.

What happens to existing emission control programs in the eight counties?

All current control programs remain in place, including the use of reformulated gas, vehicle motor inspection program, and industrial controls on volatile organic compounds (VOCs).