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Peak Daily One-Hour Ozone Averages for May 2021

The table below lists the peak daily one-hour ozone concentrations measured in May 2021 in each community where the TCEQ measures ozone. Concentrations are color-highlighted based on the EPA-defined Air Quality Index colors. (See Interpreting the AQI.) All ozone measurements are in parts per billion, and are truncated to an integer number.

The values that go into this table are calculated at 3:30 am each morning. Therefore, the current day will almost always have very low hourly averages that are not truly representative of local conditions for the day. Because of this, the report does not display the current day's data.

Use the selection boxes below to customize this report. You may select a different month, a different year, a different report format, and whether or not to include time on the report. Click on the Generate Report button once you have made your selections.

Month:Year:Report Format: Include time:
Include time
Highlight using AQI colors
AreaMonitoring SitePOCMay 2021
Dallas-Fort Worth
Ft. Worth Northwest C13/AH302 2294851426964
Keller C172274750416357
Frisco C31/C6801405756415560
Midlothian OFW C52/A1371274550436172
Denton Airport South C56/A163/X1571365256435559
Arlington Municipal Airport C611314450436563
Dallas North No.2 C63/C6791335351405158
Rockwall Heath C691314548364650
Grapevine Fairway C70/A301/X1821294749395555
Kaufman C71/A304/X0711274250404553
Granbury C73/C6811284449396863
Eagle Mountain Lake C75 1324650436354
Parker County C761304947386657
Cleburne Airport C77/C6821334756446982
Dallas Hinton St. C401/C60/AH161 3305051465964
Dallas Executive Airport C4021254447465968
Greenville C1006/A1981314852394554
Pilot Point C103213356NA425057
Italy C1044/A3231295046475274
Corsicana Airport C10511295353535055
AreaMonitoring SitePOCMay 2021
Longview C19/A127/C6442284246374557
Tyler Airport Relocated C821304953485156
Karnack C85/AFHP3031344138374445
AreaMonitoring SitePOCMay 2021
El Paso-Juarez
El Paso UTEP C12/A125/X151/G1252525057658257
Ascarate Park SE C37/A332/A172/X1591494650527248
Chamizal C41/AH126 1525056577948
Socorro Hueco C49/F3121725359607860
Skyline Park C721555358607755
Ivanhoe C414/F5141565057567557
Ojo De Agua C1021/FG121/FG2211605754NANANA
AreaMonitoring SitePOCMay 2021
Waco Mazanec C10371356049485871
Temple Georgia C1045137665444NANA
Killeen Skylark Field C10471387160456374
AreaMonitoring SitePOCMay 2021
Beaumont-Port Arthur
Beaumont-Downtown C2/A112/C2002 2294327464046
West Orange C9/A141230NA26453449
Port Arthur West C28/A128/A2281294526433951
Hamshire C64/C6541274128444253
SETRPC 40 Sabine Pass C640/C16541324825354252
SETRPC Mauriceville 42 C642/C311/C6651 N314934503950
SETRPC 43 Jefferson Co Airport C6431284325443747
Nederland High School C1035 1304627453948
AreaMonitoring SitePOCMay 2021
Austin North Hills Drive C3/A3222357055445862
Audubon C381306149405758
Dripping Springs School C6141 N297160496868
CAPCOG Lake Georgetown C6901 N366659425963
Lockhart C16041 N285744455251
St. Edwards University C16051 N306047405457
CAPCOG Bastrop CAMS16121 N315741364250
CAPCOG Elgin C16131 N335744395354
CAPCOG East Austin C16191 N316551415457
CAPCOG Round Rock Brushy Creek W C16201 N336752415558
CAPCOG San Marcos Staples Road C16751 N255645375553
AreaMonitoring SitePOCMay 2021
Houston East C1/G3162265539524644
Houston Aldine C8/AF108/X150 2285443555157
Channelview C15/AH115 3255337534042
Northwest Harris Co. C26/A110/X1542305247464448
Hou.DeerPrk2 C35/235/1001/AFH139FP2391254936574351
Seabrook Friendship Park C451233627474352
Houston Bayland Park C53/A146 1345140595967
Conroe Relocated C78/A3211265659534043
Manvel Croix Park C841335139647071
Clinton C403/C304/AH113 3254634565248
Houston North Wayside C405/C10331265038514643
Houston Monroe C4061285138555763
Lang C4082305443565055
Houston Croquet C4092324839566165
Houston Westhollow C410/C30031254033495157
Park Place C4161295237625853
Houston Harvard Street C4171295545585760
Sheldon C5511 N204733454337
Baytown Wetlands Center C5521 N233924453745
Crosby Library C5531 N225336483640
West Houston C5541 N254235484853
La Porte Sylvan Beach C5561 N313826514054
Mercer Arboretum C5571 N255147464043
Tom Bass C5581 N314838646560
Katy Park C5591 N294737504955
Atascocita C5601 N224837434040
Meyer Park C5611 N275046474649
Bunker Hill Village C5621 N264636525662
Huffman Wolf Road C5631 N275845504043
Wallisville Road C617 1 N295335474146
Texas City 34th St. C620 1 N384234505968
UH Moody Tower C6951 N285041605655
UH WG Jones Forest C6981 N295659514345
Lynchburg Ferry C1015/A165 1244636353041
Lake Jackson C1016 1304032478165
Baytown Garth C10171295540594346
Galveston 99th St. C1034/A320/X1831403934416768
UH Smith Point C16061 N343531513160
Oyster Creek C1607 1 N394236467864
UH Launch Trailer C16111 N28NA40605653
AreaMonitoring SitePOCMay 2021
San Antonio
San Antonio Northwest C232326864466673
Camp Bullis C58 1327067476572
Calaveras Lake C591326557486061
Elm Creek Elementary C5011 N286356456470
Fair Oaks Ranch C5021 N266062415561
Bulverde Elementary C5031 N266162405962
New Braunfels Airport C5041 N266049415451
City of Garden Ridge C5051 N266557446264
Seguin Outdoor Learning Center C5061 N306248405049
Heritage Middle School C6221 N306558465962
CPS Pecan Valley C6781 N164840335048
Government Canyon C16101 N276055425967
AreaMonitoring SitePOCMay 2021
Corpus Christi-Victoria
Corpus Christi West C42404738435455
Corpus Christi Tuloso C211415339455558
Victoria C871315538465455
AreaMonitoring SitePOCMay 2021
Lower Rio Grande Valley
Mission C43/AP1431356451465952
Harlingen Teege C10231364543444945
AreaMonitoring SitePOCMay 2021
Laredo Vidaurri C44/AFGP144/P2441556280565564
NA - Data not available.
 N - Data from this instrument does not meet EPA quality assurance criteria and cannot be used for regulatory purposes.

Interpreting the AQI

Air Quality Index

Each NAAQS pollutant has a separate AQI scale, with an AQI rating of 100 corresponding to the concentration of the Federal Standard for that pollutant. Additional information about the AQI and how it can be used is available from the EPA's AirNow web site.

Place your mouse pointer over the scale displayed above to view information about the Air Quality Index, and each of the rating levels.

The actual index calculation is different for each parameter measured and is specified by the EPA. The following table shows the various breakpoints used in calculating the AQI.

AQI Breakpoint Definitions
AQI Range 1hr Ozone
in ppm
8hr Ozone
in ppm
0 - 50 Not Defined 0 - 0.054
51 - 100 Not Defined 0.055 - 0.070
101 - 150 0.125 - 0.164 0.071 - 0.085
151 - 200 0.165 - 0.204 0.086 - 0.105
201 - 300 0.205 - 0.404 0.106 - 0.200
301 - 400 0.405 - 0.504 Not Defined
401 - 500 Not Defined Not Defined
500+ Not Defined Not Defined
  • The AQI for ozone is based on either the peak eight-hour running average since midnight OR the peak one-hour measurement since midnight.

PLEASE NOTE:  This data has not been verified by the TCEQ and may change. This is the most current data, but it is not official until it has been certified by our technical staff. Data is collected from TCEQ ambient monitoring sites and may include data collected by other outside agencies. This data is updated hourly. All times shown are in local standard time unless otherwise indicated.

Following EPA reporting guidelines, negative values may be displayed in our hourly criteria air quality data, down to the negative of the EPA listed Method Detection Limit (MDL) for the particular instrument that made the measurements. The reported concentrations can be negative due to zero drift in the electronic instrument output, data logger channel, or calibration adjustments to the data. Prior to 1/1/2013, slightly negative values were automatically set to zero.