Ozone is a colorless gas comprised of three oxygen atoms. It is not emitted directly into the air as a gas but is formed through a chemical reaction between nitrogen oxides (NOx) and volatile organic compounds (VOCs) in the presence of sunlight. While the ozone protects the earth from harmful ultraviolet radiation in the upper atmosphere, at ground level it is considered an air pollutant, with national standards for allowable concentrations in the ambient air. Ozone exposure causes respiratory inflammation and irritation often described as “a sunburn on the lungs” and is a trigger for increased symptoms of asthma and other respiratory illness.
Major sources of ozone precursor emissions in Utah include:
- Oil and gas exploration and production in the Uinta Basin
- Transportation emissions
- Industrial facilities
- Household products and cleaning supplies
- Paints and solvents use
Ozone Standard Background
The federal Clean Air Act requires the United States Environmental Protection Agency (EPA) to develop two types of National Ambient Air Quality Standards (NAAQS) for certain air pollutants, including ozone:
- Primary standards protect public health, including the health of groups especially affected by air pollution, such as those with a respiratory illness, children, and the elderly.
- Secondary standards protect public welfare and the environment, including protection against damage to animals, crops, and buildings.
The EPA has implemented multiple standards for ozone over the years, beginning in 1971. On October 26, 2015, the EPA revised the primary and secondary ozone 8-hour standard levels from 0.075 parts per million (ppm) to 0.070 ppm. While the state was in attainment under the previous 8-hour ozone standard, all or parts of seven Utah counties did not meet the new 8-hour ozone standard. Nonattainment designation to the NAAQS is determined by the EPA when an area or areas within a state persistently exceed the NAAQS. The EPA published ozone nonattainment designations for the 2015 NAAQS in the federal register on June 4, 2018, with an effective date of August 3, 2018.
Wasatch Front Nonattainment Designation
On June 4, 2018, the EPA designated the Wasatch Front as marginal nonattainment, the least stringent nonattainment designation, for the 2015 8-hour ozone standard. The portions of the Wasatch Front affected by this designation have been divided into two areas: Northern Wasatch Front and Southern Wasatch Front. The Northern Wasatch Front includes all or part of Salt Lake, Davis, Weber, and Tooele counties. The Southern Wasatch Front includes parts of Utah county.
The Wasatch Front was required to attain the standard by August 3, 2021. The Southern Wasatch Front nonattainment area attained the standard and the DAQ has initiated the process for redesignation to attainment for this area.The Northern Wasatch Front nonattainment area did not attain the standard by that date and was subsequently bumped up to moderate classification on November 7, 2022.
As a result of this designation, the Utah DAQ is developing a moderate SIP to address all Clean Air Act requirements and overview the state’s efforts to reduce ozone-forming emissions. This SIP is scheduled to be submitted to the EPA by August of 2023. However, monitoring data collected in the Northern Wasatch Front nonattainment area indicates that the area will likely not attain the standard by the moderate attainment date and will likely be further designated as a serious nonattainment area in 2025.
Uinta Basin Nonattainment Designation
On June 4, 2018, the EPA designated portions of the Uinta Basin as marginal nonattainment, the least stringent nonattainment designation, for the 2015 8-hour ozone standard. This designation applied to areas in Uintah and Duchesne Counties below a contiguous, external perimeter of 6,250-feet elevation. The Uinta Basin nonattainment area was required to attain the ozone standard by August 3, 2021. The Uinta Basin did not obtain the ozone standard by August 3, 2021, however the area experienced ozone levels below the standard in the years 2020 and 2021 allowing the state of Utah to request two one-year extensions to the attainment date. The area was granted the first one-year extension in November 2022, moving the attainment date to August 3, 2022. The area is awaiting the decision by EPA Region 8 on the second one-year extension and still remains a marginal nonattainment area. Challenges with air quality in the area continue to be studied and evaluated; however, a recent Federal Implementation Plan finalized by EPA Region 8 for the Uinta Basin, as well as proposed national oil and gas methane rules should help reduce emissions from oil and gas sources and help with the continued improvement of air quality in the area.
Utah Ozone Nonattainment Map
Utah ozone nonattainment map, which includes the nonattainment area boundaries and the townships and ranges of the legal description.