3C: Wasatch Front ozone

Kim Frost | Chapter Three: Air

TAKEAWAY

Summertime ozone will continue to pose health and regulatory challenges for Utah’s urban areas.

EPA reclassified the northern Wasatch Front from “marginal” to “moderate” nonattainment.

Utah’s urban center experiences harmful air pollution—ozone—during the summertime. Ozone is a highly reactive gas that causes damage to human lung tissue. Ground-level ozone is generated when precursor pollutants—volatile organic compounds (VOCs) and oxides of nitrogen (NOx)—interact with sunlight. The northern Wasatch Front region experiences ozone concentrations that exceed U.S. Environmental Protection Agency’s air quality thresholds.

Earlier this year, the EPA reclassified the northern Wasatch Front as “moderate” nonattainment. This is a bump up from the previous “marginal” designation. This designation requires the state to submit a state implementation plan showing how the state will reduce precursor emissions in the nonattainment area and an attainment demonstration. The plan is due January 2023, and the attainment date is August 2024.

Many sources of pollution are already regulated through past state implementation plans and other rulemaking efforts; however, one source that has been largely unregulated is lawn and garden equipment. Two-stroke gas powered lawn and garden equipment contributes a significant amount of pollution in the summer. As a result, the Utah Division of Air Quality hopes to create a large multi-year incentive program to help replace gas-powered equipment with cleaner electric equipment.

There are serious potential consequences if the area fails to attain the health-based standard. The federal government can potentially freeze federal highway funds and put in place a far stricter federal implementation plan. However, of far greater importance is the need to reduce ozone to protect Utahns’ health and improve quality of life along the Wasatch Front.

Line graph of ozone concentration in ppm in the cities of Hawthorne, Bountiful, and Harrisville from 1994 to 2020. Vertical axis values range from 0.60 ppm to 0.90 ppm. Three lines represent the ozone concentrations in the cities of Hawthorne, Bountiful, and Harrisville respectively. These lines follow the same general trends and show a slight decrease in ozone concentrations over the years sampled. Ozone levels in these cities reached a maximum in Bountiful in 1998 when ozone concentration levels were at about 0.87 ppm. The minimum ozone concentration over the years sampled was just over 0.70 ppm in Harrisville in 2011 and 2019.
Bar graph of the number of days that the 8-hour ozone daily max exceeded 0.070 ppm in Salt Lake City for the years 2000 through 2022. Vertical axis values range from 0 days to 60 days. Each bar is split into up to three regions, one region labeled "Very unhealthy" and representing the days that 8-hour ozone daily max exceeded 0.106 ppm, one region labeled "Unhealthy" and representing the days that the daily max was within the range 0.086 ppm to 0.105 ppm, and one region labeled "Unhealthy for sensitive groups" and representing days that the daily max was within the range 0.071 ppm to 0.085 ppm. These sections show that 3 to 5 days total over the years 2000 to 2022 were in the "Very unhealthy" category, while there were between 1 and 10 days in the "Unhealthy" category during most of the years sampled. The vast majority of days tracked on the graph were in the "Unhealthy for sensitive groups" category. Recent years have relatively many days above 0.070 ppm but relatively few above 0.085 ppm. The five years in which there were the most days that the 8-hour ozone daily max exceeded 0.070 ppm are 2006 and 2007 (with 40 days), 2021 (with 39 days), 2018 (with 38 days), and 2017 (with 36 days). The years with the lowest tracked 8-hour ozone daily max were 2010 and 2014 at 7 days each year.