Air Quality in San Antonio, Texas — Live
Live readings from PurpleAir sensors across San Antonio — with free alerts the moment the air turns.
Live San Antonio AQI from nearby PurpleAir sensors loads when this page opens in a browser, along with a live sensor map covering San Antonio and New Braunfels, Schertz, Helotes, Converse.
San Antonio's air problem is ozone, and on paper it has been getting worse rather than better. Bexar County was first designated nonattainment for the 2015 federal ozone standard in September 2018 at the mildest classification, Marginal. It moved to Moderate effective November 2022, and on 22 July 2024 it was reclassified again, to Serious. The county now has until 24 September 2027 to meet the standard, with the 2026 ozone season as the attainment year, and the tier after Serious is Severe. None of this is visible from a window. Ozone is a colourless gas that builds on hot, still afternoons, so the worst days here usually look like nice days.
Canairy watches the sensors around your home, your kids' school, and everywhere else you care about, and tells you in plain English when the air changes enough to matter.
Bexar County is the nonattainment area, and only Bexar County
The 2015 ozone nonattainment area for San Antonio is Bexar County on its own. Atascosa, Bandera, Comal, Guadalupe, Kendall, Medina and Wilson are all designated attainment or unclassifiable, so someone in New Braunfels or Boerne lives outside the regulated area while breathing much the same air on a bad day. The line is a regulatory boundary drawn around monitors, not a wall. Ozone forms downwind of where its ingredients are emitted, which is why the highest readings in a metro are often taken well away from the traffic that helped make them.
The ladder Bexar County has climbed explains why local rules keep tightening. Marginal in 2018 brought almost no new obligations. Moderate in 2022 required an attainment demonstration. Serious, effective 22 July 2024, lowers the threshold at which a business counts as a major source and adds tougher permitting and offset requirements. It followed the county missing its moderate deadline, and the State of Texas asked the EPA for the reclassification rather than waiting to be pushed into it.
The quarries and kilns along the north side
The Balcones Escarpment that gives north San Antonio its hills is limestone, and limestone is what cement is made from. Alamo Cement runs a kiln and quarry at 6055 W. Green Mountain Road on the far north side under TCEQ air permit 6758, and Vulcan Materials operates the 1604 Quarry at 4303 N Loop 1604 East, out near Stone Oak. These are permitted industrial neighbours to a great deal of housing that was built long after they opened.
Day to day this shows up as dust rather than a citywide AQI swing. Crushing, hauling and blasting throw coarse particles that mostly settle within a mile or two, so the effect registers on the sensor nearest you far more than on a city average. If you live within sight of a quarry face, a single sensor on your own block will tell you more than any regional number ever will.
The Eagle Ford gas fields sit upwind on a south wind
The Eagle Ford Shale runs in an arc across South Texas below San Antonio, close enough to matter. Modelling work by the Alamo Area Council of Governments with the TCEQ estimated the play could add as much as 7 parts per billion to San Antonio's ozone. Against a standard of 70 ppb, that is not a rounding error for a county that has spent years sitting a whisker over the line.
The prevailing summer wind here is from the south and southeast, which is the direction the fields lie in. It is the same flow that brings Gulf moisture up. So the setup for a bad ozone day in San Antonio is usually a warm, humid, light southerly afternoon rather than anything dramatic.
San Antonio air quality FAQ
Why is there smoke in San Antonio today?
Most bad-air days in San Antonio involve no smoke at all. The pollutant that keeps the county in nonattainment is ozone, which is invisible and odourless, so the worst afternoons look perfectly clear. When there is genuine smoke it is usually a grass or brush fire during a drought summer, or land-clearing burning in the surrounding counties. A quick check: if the sky looks hazy but the sensors near you read low PM2.5, you are probably looking at humidity rather than particles.
What is the air quality in San Antonio right now?
This page shows the live AQI for San Antonio from PurpleAir sensors across the city, updated continuously. Bear in mind that PurpleAir sensors measure fine particles, PM2.5, while San Antonio's regulatory problem is ozone. A Good particle reading on a hot July afternoon does not mean the ozone is fine, so on those days it is worth checking an ozone forecast as well.
Why did San Antonio's ozone classification get worse?
Because the county missed its deadlines. Bexar County was designated Marginal nonattainment for the 2015 ozone standard in September 2018, reclassified to Moderate effective November 2022, and reclassified again to Serious effective 22 July 2024 after failing the moderate attainment deadline. Serious carries a 24 September 2027 deadline based on the 2026 ozone season, plus tighter permitting thresholds for industry in the meantime.
Does the Eagle Ford Shale affect San Antonio's air?
It appears to. Work by the Alamo Area Council of Governments with the TCEQ estimated that emissions from the Eagle Ford play, which lies south of the city, could raise San Antonio's ozone by up to 7 parts per billion. The fields sit in the direction of the prevailing summer wind, so their contribution is largest on exactly the warm southerly days when ozone is already forming fastest.
What AQI level is unhealthy?
Under the US EPA scale, AQI 0–50 is Good and 51–100 is Moderate. From 101 the air is Unhealthy for Sensitive Groups — kids, older adults, and people with asthma or heart conditions — and above 150 it's Unhealthy for everyone. Canairy translates these numbers into a plain-English verdict, like whether to close the windows or move a workout indoors.
Is Canairy free?
Yes. The Canairy app is free to download and includes live air quality for all your saved places, plain-English verdicts, and free push alerts when the air crosses your threshold. A paid plan adds extras like SMS text alerts.
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