Ozone
The current nonattainment areas were designated as being in marginal nonattainment of the ozone NAAQS of 0.070 parts per million (ppm) effective on August 3, 2018. Since then both ozone areas have been reclassified twice for not meeting the NAAQS by the attainment date and are now classified as being in serious nonattainment. The controlling Monitor design values within the two nonattainment areas are currently 0.078 ppm (Kenosha) and 0.074 ppm (Milwaukee).
Attainment Dates by NAA Classification
NAA class |
8-hour ozone design value (ppm) |
Primary standard attainment date |
Marginal |
0.071 to 0.080 |
August 3, 2021 |
Moderate |
0.081 to 0.092 |
August 3, 2024 |
Serious |
0.093 to 0.104 |
August 3, 2027 |
Severe-15 |
0.105 to 0.110 |
August 3, 2033 |
Severe-17 |
0.111 to 0.162 |
August 3, 2035 |
Extreme |
0.163 or greater |
August 3, 2038 |
Note: Bold text indicates current ozone nonattainment classification of both ozone NAA in Southeastern Wisconsin
Source: EPA
Current and historical monitor data can be found in the WDNR Air Quality Trends Report.
PM2.5
The current maintenance area was initially designated as nonattainment of the primary NAAQS for PM2.5 (12 μg/m3) on October 9, 2009. The Wisconsin DNR Submitted a redesignation request on June 5, 2012. EPA redesignated the area as maintenance effective April 22, 2014. Monitor design values within Southeastern Wisconsin are currently 9 μg/m3 or less.
Effective May 6, 2024, the EPA finalized a new lower primary PM2.5 NAAQS (9 μg/m3). Area designations are expected to be completed in 2026. More information on next steps can be found at the EPA and WDNR websites.
Current and historical monitor data can be found in the WDNR Air Quality Trends Report.