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Ozone Standard
2018 State of the Environment Report (AQ)

In October 2015, EPA finalized a new 8-hour ozone standard that lowered the ozone standard from 75 parts per billion (ppb) to 70 ppb. DAQ was given one year to evaluate statewide air-monitoring data to determine which areas met the new standard.

DAQ completed its ozone area designation review and five-factor analysis in September 2016 and recommended three ozone nonattainment areas (3.93 MB) for the governor’s consideration:

  • Portions of Utah County currently nonattainment for PM5
  • Portions of Weber, Davis, Tooele, and Salt Lake counties currently nonattainment for PM5
  • Portions of the Uinta Basin that are at or below 6,000 feet in elevation and within jurisdictions subject to state air-quality regulation

The division recommended that Box Elder, Cache, Carbon, Garfield, San Juan, and Washington counties be designated as ozone attainment areas, and areas without monitoring data be designated as unclassifiable/attainment until sufficient monitoring data were collected. Governor Herbert made a formal recommendation (3.93 MB) to EPA on behalf of the state based on this DAQ staff analysis.

In June 2017, EPA determined there was insufficient information to complete area designations and extended the deadline by one year for states to submit their ozone measurements to the agency. EPA reversed course a few months later, and on August 2, 2017, announced it would, in fact, not seek a delay in the implementation of the 2015 ozone standard (214.6 KB).

On November 6, 2017, EPA issued a notice (2.45 MB) with initial air-quality designations for the 8-hour 2015 ozone standard. The agency determined that most areas in the country were either in attainment or unclassifiable. Per DAQ’s recommendation, Beaver, Emery, Garfield, Iron, Kane, Millard, Piute, San Juan, Sevier, Washington, and Wayne counties were designated attainment/unclassifiable for the standard.

On June 4, 2018, EPA issued designations for the remaining areas of the country. The agency accepted the governor’s recommendation with a modification to the Uinta Basin. EPA designated three nonattainment areas:

  • Portions of Utah County (Southern Wasatch Front Nonattainment Area)
  • Portions of Weber, Davis, Tooele, and Salt Lake counties (Northern Wasatch Front Nonattainment Area)
  • Portions of the Uinta Basin at or below 6,250 feet in elevation and within jurisdictions subject to state air-quality regulation (Uinta Basin Nonattainment Area)

All nonattainment areas are classified as Marginal, meaning a SIP is not required. The remaining counties of the state were designated attainment/unclassifiable.

Utah, along with other western states, has elevated background ozone, often in high-elevation, rural areas far from manmade pollution sources. This background ozone comes from wildfires, stratospheric intrusions, and domestic and intercontinental ozone transport. EPA has indicated that it will work closely with Utah to find ways to comply with the new standard while taking into account exceedances potentially caused by background ozone.