Ozone NAAQS Summary and Coalition Letter

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The Honorable Andrew Wheeler
Administrator
U. S. Environmental Protection Agency
200 Pennsylvania Avenue, N.W.
Washington, DC 20460
RE: Docket EPA-HQ-OAR-2018-0279 Review of the National Ambient Air Quality Standards for Ozone

Dear Administrator Wheeler,

The under signed organizations agree with the accompanying analysis that the adoption of a more stringent ozone National Ambient Air Quality Standard in 2015 was a mistake that will be compounded by your preliminary decision to retain that standard. We encourage you to re-consider your initial decision by returning to a 75 parts per billion (PPB) limit while also reconsidering the form to adopt the use of the 7^th highest day. A review of ozone Non- Attainment Area (NAA) boundaries and the designation process for Exceptional Events are also recommended.

The current form appropriately uses the 4^th highest day dismissing the three highest days to allow for peak day levels associated with meteorological extremes. However, in three of the last four completed years smoke from extreme western wildfires have grossly impacted continent wide ozone levels on four to five days a year. This year fires may have a similar impact. These events often cause ambient levels to exceed 80 PPB as far away as Philadelphia and New York. We recommend adopting either the 7^th highest day form, or the EPA could declare Exceptional Events from wildfire smoke (Clean Air Act Section 319), that acts as an ozone precursor, without waiting for time consuming individual state petitions. This change should be accompanied by including forest management plans in State Implementation Plans for states with ozone NAAs to reduce wildfire risk. This might allow a return to the 4^th highest day form in the next ozone standard review in 2025.

The included analysis is based on a detailed review of 2019 and 2020 Air Quality Monitoring (AQM) data for all counties in NAAs. There are 90 million people in 149 counties meeting, or marginally over, the current standard. Providing economic relief to them, with low risk of exposure to high levels of ozone, by returning to a 75 PPB standard would allow a stronger focus on the 37 million people in 34 counties who still live with unhealthy air.

There is new information in both the EPA review and the included analysis to support these changes to the ozone standard:

1. A key study used in 2015 to set the current standard based on potential cardiovascular mortality has been discredited by the EPA review. This removes a key factor supporting the current standard.
2. EPA computer models show exposure risks of sensitive populations to days over 73 PPB have been cut in half, and even that is a conservative estimate based on out of date 2015-2017 data corrupted by two years of high smoke levels from western wildfires.  Actual, relatively smoke free 2019 ozone data by county shows exposure risk targets adopted in support of the current standard can be met with a 75 PPB standard.
3. Using national trend data from the EPA, ambient NO2 dropped about 5 PPB from 2012 to 2019, and ozone dropped 10 PPB. NO2 is a marker for manmade ozone precursors. During the peak of the COVID-19 lockdowns from 3/22/2020 to 4/20/2020, NO2 also dropped 5 PPB compared to 2019, but ozone only fell 3 PPB, one third as much as the 2012 to 2019 period. This suggests we have reached the point of diminishing returns in reducing ozone precursors through regulation of manmade emissions. The current standard is probably set too close to background levels to accommodate normal weather-related variations in ambient concentrations. A 75 PPB standard corrects this problem.