EPA Will Designate Kenosha County as Nonattainment for Ozone

Citing data from the state of Illinois, the EPA has announced it intends to revise its proposed designation for Kenosha County, and recommend it be designated nonattainment for the 2008 8-hour ozone standard. This decision by the EPA is unwelcome, as nonattainment designations carry with them substantial regulatory and related economic burdens.


Section 109 of the Clean Air Act requires the EPA to establish National Ambient Air Quality Standards (NAAQS) for several types of air pollutants. Using this authority, the EPA has created standards for six air pollutants: sulfur dioxide (SO2), particulate matter (PM2.5), nitrogen dioxide (NO2), carbon monoxide (CO), ozone, and lead.

In 1997, EPA set the 8-hour ozone standard at 80 parts per billion (ppb). In 2008, EPA created a new 8-hour standard, lowering it from 80 ppb to 75 ppb. Soon after President Obama was sworn into office, the EPA announced it would reconsider the 2008 standard, and likely propose a new ozone standard in a range of 60 to 70 ppb. Under pressure from industries suffering in the bad economy, President Obama asked the EPA to withdraw its proposed ozone standard revision on September 2, 2011.

After the President withdrew the 2010 reconsideration, the EPA released a memo announcing that it would begin implementing the 2008 8-hour ozone standard. On December 9th, 2011 the EPA notified states of its proposed determinations, and Sheboygan County, Wisconsin was the only Wisconsin area listed as proposed nonattainment. At that time, the EPA also indicated that it would be reevaluating its designation of Kenosha County as attainment based on 2011 air quality data submitted by Illinois two days before the EPA announced its proposed designations.

Revised Designation

On December 7, 2011, Illinois sent its 2011 certified air quality data to the EPA for consideration in the ozone designation process. The 2011 ozone data indicates a monitored violation of the 2008 ozone standard at the Zion monitor in Lake County, Illinois, which is part of the Combined Statistical Area (CSA) that includes Chicago and Kenosha County, Wisconsin.

Because the data indicates an ozone level violation, the EPA announced on January 31, 2012 that intends to designate the Chicago-Naperville, Illinois-Indiana-Wisconsin area as nonattainment, with boundaries that include: Kenosha County in Wisconsin; Lake, Porter, and Jasper Counties in Indiana; and several counties in Illinois.

The technical support document provides the technical and qualitative bases for the intended boundaries of the Chicago-Naperville, IL-IN-WI ozone nonattainment area. Kenosha County has not been a part of the Chicago nonattainment area in the past. The county was instead included in the Milwaukee-Racine, Wisconsin ozone nonattainment area for the 1997 ozone standard, which the EPA has proposed to designate as attainment for the 2008 standard.

The VOC and NOx emissions in Kenosha County, precursors to ozone pollution, are relatively low and similar to those for counties recommended for exclusion from the intended ozone nonattainment area. In addition, it is noted that Illinois’ and Wisconsin’s wind direction analyses for high ozone days indicate that Kenosha County emissions are probably downwind of the violating Zion, Illinois monitor on high ozone days. These conclusions would support the exclusion of Kenosha County from the intended ozone nonattainment area.

However, the EPA thinks that it is appropriate to include it in the Chicago nonattainment area now because historically the Chiwaukee Prairie monitoring site in Kenosha County, Wisconsin has been the high downwind monitoring site for the Chicago region. The Chiwaukee Prairie ozone design value was used to establish the classification for the Chicago-Gary-Lake County, IL-IN ozone nonattainment area under both the 1997 8-hour ozone standard and the 1-hour ozone standard. In addition, monitoring data from this monitoring site was historically used by the States of Illinois, Indiana, and Wisconsin in conjunction with modeled ozone concentrations to demonstrate that emission reductions in the Chicago area were sufficient to attain the 1-hour ozone standard and the 1997 8-hour ozone standard.

Future Action

The EPA notes that if the State of Wisconsin submits certified data for 2009-2011 within the 120 day period it has to respond to the designation letter, showing that Kenosha County is actually attaining the 2008 8-hour ozone standard, EPA’s conclusion regarding the designation for Kenosha County should be revisited.

The EPA will be publishing a notice in the Federal Register to announce the availability of the January 31, 2011 letters and to provide for a public comment period limited to the revised responses. The public will have 30 days after the notice is published in the Federal Register to comment on the letters.

The EPA plans to make final designations in spring 2012.

Additional information about the 8-Hour Ozone standard is available on the Great Lakes Legal Foundation Regulatory Watch website.

This post, authored by Emily Kelchen, originally appeared on the Great Lakes Legal Foundation Regulatory Watch Blog.