Bexar County has a new air quality status as of November 7, 2022. The US Environmental Protection Agency (EPA) has downgraded the region’s ozone nonattainment designation from Marginal to Moderate. AAMPO updated the Transportation Conformity Document to meet requirements of this new status. But what does this mean for the air we breathe in Bexar County? Will it get worse before it gets better?
Ozone Levels in Bexar County
Ozone, commonly called smog, is the only pollutant in Bexar County that exceeds EPA standards. This and other pollutants and substances, such as pollen, can still affect residents sensitive to diminished air quality. Despite the new designation, peak ozone levels have been steady since 2016, and have reduced by 9% since 2012. Also, no severe exceedance days, where ozone levels are 20% or more above the standard, have been recorded since 2018—which was the year Bexar County was first designated as nonattainment.
The source of ozone is a complex topic. Ozone is formed when sunlight interacts with precursor pollutants, nitrous oxides (NOx) and volatile organic compounds (VOCs). Most ozone in the region—about 80%—is “background ozone” which is formed in other parts of Texas, or even other states and countries. Ozone formed within the region is mainly from non-transportation sources such as industrial plants and dry cleaners. In fact, of the ozone produced in Bexar County, 30% is from cars, trucks, and vans, or 5% of total ozone when impacts from other sources/areas are considered. AAMPO’s focus is on this 5%, a small amount with a significant impact on meeting air quality goals.
Future Emissions Projections
To play our role in meeting EPA requirements, AAMPO uses computer simulations to project traffic patterns and resulting emissions. AAMPO must show emissions will be below pre-nonattainment 2017 levels and less than the emissions if no new transportation projects are introduced until 2050—the horizon year of the long-range transportation plan. The model has shown a drastic decrease in ozone precursors since 2018, and despite planning for a transportation network to support nearly twice our current population, the precursor levels are projected to stay roughly the same between 2025 and 2050.
Air Quality Improvements
AAMPO was able to meet EPA testing requirements through the use of our Congestion Mitigation and Air Quality program (CMAQ). CMAQ is a special federal grant program for nonattainment areas to implement projects that reduce pollutants and congestion. These projects will reduce emissions by several tons per year. Another factor is more strict emissions standards for new cars. As older vehicles stop working, they are replaced by newer and cleaner vehicles. Despite a rapidly growing region, AAMPO is working with local, state, and federal partners to ensure air quality is improved.
