The United States Environmental Protection Agency (USEPA) has recently redesignated the Cleveland, Ohio, area as being in “attainment” of the 2015 ozone National Ambient Air Quality Standards (NAAQS),1 reversing its previous nonattainment designation for ground-level ozone. NAAQS are federal air quality standards established under the Clean Air Act to protect public health and the environment. This redesignation is significant because it may affect air permitting requirements for facilities in the region, including major source thresholds and applicable permitting programs.
In 2015, USEPA revised the NAAQS standard for ozone from 0.075 part per million (ppm) to 0.070 ppm,2 in an effort to increase the protection of public health against the effects of ozone for both the short and long term. In 2018, the Cleveland area was designated as nonattainment for the revised 2015 NAAQS for ozone after monitoring data indicated levels exceeding the revised federal standard. In January 2025, USEPA further reclassified the area from moderate to serious nonattainment.3
USEPA issued a final rule in June 2026, approving the Ohio Environmental Protection Agency’s request to redesignate the Cleveland, Ohio, area to attainment status. This determination was based on ambient monitoring data for the 2023–2025 period demonstrating attainment of the 2015 ozone NAAQS. Importantly, USEPA’s determination relied on the Ohio Environmental Protection Agency’s Exceptional Events demonstration, which showed that certain ozone exceedances were significantly influenced by emissions from wildfire smoke events and should therefore be excluded from regulatory attainment calculations under the Exceptional Events Rule. After excluding the affected monitoring data, the Cleveland area met the federal ozone standard and qualified for attainment status.4
Following redesignation, federal law requires a maintenance plan to keep the area in attainment for at least 10 years. As of June 2026, the Ohio State Implementation Plan has been revised to demonstrate that the state will maintain the 2015 ozone NAAQS in the Cleveland area through the year 2038. The designated Cleveland area includes Cuyahoga, Geauga, Lake, Lorain, Medina, Portage, and Summit counties.
How does this affect your facility?
This redesignation is expected to affect air permitting requirements in the Cleveland area by increasing potential-to-emit (PTE) thresholds for major sources of ozone precursors, volatile organic compounds (VOCs) and nitrogen oxides (NOx). It will also shift applicable control technology requirements from lowest achievable emission rate (LAER) under the Nonattainment New Source Review (NNSR)5 program to best available control technology (BACT) under the Prevention of Significant Deterioration (PSD) program. Key changes from the redesignation include the following:
- NNSR requirements are replaced by PSD requirements.
- PSD: Major modification significance level.
- LAER requirements are replaced by BACT requirements. While LAER represents the most stringent control technology available, BACT is control technology justified and based on economic, energy, and environmental impacts.
- Emission offsets for NOx and VOC emissions are no longer required, as long as NAAQS are not exceeded.
- Major source thresholds and major modification thresholds for VOC and NOx emissions increase, as summarized in the following table.
Comparison of NNSR and PSD Permitting Thresholds for VOC and NOx Emissions
| Requirement | Nonattainment (NNSR) | Attainment (PSD) |
|---|---|---|
| Major source threshold | 50 tpy VOC or NOx | 100 tpy VOC or NOx |
| Major modification threshold | 25 tpy VOC or NOx | 40 tpy VOC or NOx |
tpy = tons per year
What is ground-level ozone?
Ground-level ozone, unlike naturally occurring atmospheric ozone in the stratosphere, is a pollutant formed within the troposphere through photochemical reactions between NOx and VOCs in the presence of sunlight and elevated temperatures.6
Ground-level ozone is a key component of smog and can have harmful effects on human health. Exposure to elevated ozone concentrations can cause respiratory effects, including coughing, throat irritation, chest discomfort, and reduced lung function, particularly among individuals with asthma, children, older adults, and people who spend significant time outdoors, including outdoor workers.7 In addition to its health impacts, ozone can damage vegetation, reduce crop yields, and negatively affect ecosystems.
If you are concerned about ozone levels in your area, please visit the EPA AirNow app for local air quality and ozone forecasts.
Questions? We’re here to help.
For support with compliance or to discuss any questions or concerns you may have, please contact Taylor Wheelon at Taylor.Wheelon@ehs-support.com or Katie Milk at Katie.Milk@ehs-support.com.
Sources:
1 USEPA. (2025, December 18). Ozone National Ambient Air Quality Standards (NAAQS).
2 USEPA. (2015, October 26). Final Rule: National Ambient Air Quality Standards for Ozone. 80 Federal Register 65292.
3 Ohio Environmental Protection Agency. (2024, November). National Ambient Air Quality Standard (NAAQS) for Ground-Level Ozone. Division of Air Pollution Control.
4 USEPA. (2026, June 23). Final Rule: Air Plan Approval; Ohio; Redesignation of the Cleveland, OH Area to Attainment of the 2015 Ozone Standard. EPA-R05-OAR-2025-3654.
5 USEPA. (2025, December 15). Nonattainment NSR Basic Information.
6 USEPA. (2026, February 18). Ground-level Ozone Basics.
7 USEPA. (2026, February 24). Health Effects of Ozone Pollution.
