live AQI index
|Air pollution level||Air quality index||Main pollutant|
|Good||17 US AQI||PM2.5|
|Open your windows to bring clean, fresh air indoors|
|Enjoy outdoor activities|
|Friday, Jul 31|
Good26 US AQI
|Saturday, Aug 1|
Good28 US AQI
|Sunday, Aug 2|
Good29 US AQI
Good31 US AQI
|Tuesday, Aug 4|
Good33 US AQI
|Wednesday, Aug 5|
Good30 US AQI
|Thursday, Aug 6|
Good30 US AQI
|Friday, Aug 7|
Good28 US AQI
|Saturday, Aug 8|
Good17 US AQI
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San Antonio's annual air quality averages a US air quality index, or AQI, of “good.” In 2019, monthly averages ranged from AQI 25 (“good”) in October to AQI 54 (“moderate”) in May. Spring and summer tend to be more polluted than the fall and winter. May, July, and June were San Antonio’s most polluted months, respectively, with average AQIs of 54, 44, and 43.
Despite clean annual averages, daily fluctuations can contribute to unhealthy pollution events. The San Antonio area had 49 days of unhealthy, ‘nonattainment’ air pollution in 2018.1 Unhealthy days are defined as days in which either PM2.5 or ozone levels exceeded the federal threshold for 8-hour pollution. Most often, unhealthy days were the result of high ozone.
Ozone is a gas molecule, described as ‘smog’ at ground-level. Unlike most pollutants, ozone is not emitted directly into the atmosphere but rather is formed in the air from precursor pollutants reacting in sunlight. This property makes ozone more difficult to control and regulate, particularly in warm urban environments that have ideal conditions for ozone formation.
In 2019, San Antonio was rated an “F” for ozone pollution according to the American Lung Association’s State of the Air report.2 The city moreover ranked 38th for high ozone nationally out of 229 included metropolitan areas. Current ozone levels (~73 ppb) are estimated to contribute to nearly 4,700 deaths annually.3 Improving ozone levels to less than 68 ppm could save roughly 24 lives per year. Conversely, should ozone levels deteriorate to 77 ppm, it is estimated that an additional 19 deaths could result annually.
Follow live air quality data in San Antonio at the top of this page, and use San Antonio’s forecast air quality data to plan ahead and take precautionary measures to reduce your pollution exposure.
In recent years, San Antonio’s air quality has worsened. This comes despite long-term improvements since the Clean Air Act of 1970.
For fine particulate matter, or PM2.5, San Antonio experienced a 17.5% increase in pollution levels from 2018 to 2019. San Antonio’s recent air pollution jumps may be attributable to fracking at the relatively new Eagle Ford shale facility 50 miles from the city as well as to a drastic increase in illegal air pollution from nearby industrial facilities.4
According to a study published by Environment Texas and Frontier Group, Texas industrial facilities reportedly released 135 million pounds of illegal air pollution in 2018, or more than double the amount from the previous year. Weak penalties and enforcement are likely to have directly incentivized these increases. The penalties for illegal emissions from all Texas facilities only amounted to $2 million in 2018, or roughly one cent per pound of illegal air pollution. That number is less than 1/100th of what they could have charged ($297 million) under existing law. Texas’s business-first approach, in the face of resident health, presents a significant challenge to tackling air pollution levels in the state and in San Antonio specifically.
Fracking is also thought to have increased city-wide ozone levels. Since Eagle Ford shale, one of the nation's largest oil and gas developments, was established just outside of the city, ozone levels have increased significantly.5 Data collected by InsideClimate News found that during the months of April to October, the months in which San Antonio’s ozone levels were the highest, oil and gas development accounted for half of all ozone-forming precursor pollutants in the atmosphere.
Many health and environmental experts advocate that the current federal ozone standard of 70 ppb doesn't do enough to safeguard public health. There is pressure for the EPA to further lower the standard to around 60 ppb. As San Antonio continues to fail the present 70 ppb standard, and air pollution levels appear to be on the rise, it is clear that more must be done to reduce emissions from the largest polluting sources: transportation and the oil and gas industry.
Transportation remains the leading source of air pollution in San Antonio. According to a report from Frontier Group and the Environment America Research & Policy Center, it is estimated that more than half (52%) of all PM2.5 and ozone pollution in Texas originates from transportation exhaust. San Antonio is a relatively dispersed city in Bexar county. The area is home to more than 2 million residents and 1.6 million registered vehicles.6 According to the 2017 census, nearly 80 percent of workers in San Antonio drive to work everyday by themselves.7 The average commute was 24 minutes, or 48 minutes to work and back.
In an effort to reduce transportation emissions, San Antonio’s EV-SA has been established to plan efforts around electric transportation. The city currently offers a $2,500 rebate incentive for consumer electric vehicles and further allows electric vehicle owners to park for free at city managed street parking meters.8 San Antonio is further attempting to “lead by example” in transitioning 85 percent of the city’s administrative vehicles to electric, hybrid, and fuel-efficient vehicles by 2020.
Petroleum-related industrial activity accounts for the next largest portion of PM2.5 and ozone, giving rise to roughly 21% to state’s pollution.9 Emissions in this sector have continually exceeded regulations, with very little penalty and enforcement. From 2017 to 2018 alone, emissions from petroleum activity in Texas doubled. Fines have not been charged to the fullest extent of the law, making it in a petroleum business’ best interest to over-pollute.
Geographically, San Antonio is located in a valley. Weather tends to move winds from the southeast to the northwest, bringing Gulf air to the city.7 These events can contribute to temperature inversions, a phenomena in which warm air above traps cooler air below, contributing to an accumulation of surface air pollution. While many cooler locations commonly experience inversion patterns in the winter, this weather event is much more common during the summer in San Antonio.
Surprisingly, the majority of San Antonio’s air pollution comes from locations outside of the city limit, according to the Alamo Area Council of Governments (AACOG).10 Roughly 16 percent is estimated to come from the rest of the U.S. (including other parts of Texas), while another 25 percent comes from the rest of North America. According to this report, the largest portion, 38 percent, is from other global locations outside of North America. In order for San Antonio to attain federally mandated pollution levels, significant changes must be made to its own city-wide emissions, which contribute 20.5 percent of air pollution. Such regulations must focus on cleaner energy, especially in the transportation sector, and on stricter emission regulations of surrounding industrial businesses.
San Antonio’s AQI can vary from location to location, even within the city. Use San Antonio’s air pollution map to understand the impact of local emission sources.
+ Article Resources
 Environment Texas Research and Policy Center. (2020). Trouble in the air millions of Americans breathed polluted air in 2018.
 American Lung Association. (2020). State of the air – 2019.
 Palacios J. (2017). Deteriorating air quality in San Antonio could mean more respiratory deaths.
 Nowlin S. (2019). Illegal air pollution has increased exponentially in the San Antonio area, according to new report.
 Song L., What's behind surging ozone pollution in Texas? Study to weigh role of fracking in health hazard.
 San Antonio District statistics: vehicles registered. (2019).
 Hardin W. (2019). The air you breathe: San Antonio’s air quality & helping kids with asthma.
 City of San Antonio. (2020). Electric vehicles San Antonio.
 Ridlington E., et al. (2020). Trouble in the air: millions of Americans breathed polluted air in 2018.
 Friedman C. (2018). Most of San Antonio's air pollution comes from other cities, countries, AACOG says.