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Four Highest Eight-Hour Ozone Concentrations in 2021
as of January 24

Use this form to retrieve the four highest eight-hour ozone concentration averages from data collected at TCEQ monitoring sites beginning December 14, 2005 through today. Although this is our most current data, it is not considered official until it has been certified by our technical staff. This information is updated hourly. All times shown are in Local Standard Time.

The table below lists the four highest daily maximum eight-hour ozone concentrations measured in 2021 in each community where the TCEQ measures ozone. Concentrations that are rated Moderate or higher are color-highlighted based on the EPA-defined Air Quality Index colors. (See Interpreting the AQI.) The fourth-highest average is in bold black (unless it is highlighted). All ozone measurements are in parts per billion. Times are shown in 24-hour format and correspond to the beginning of the eight hour average.

Use the selection boxes below to customize this report. You may select a different year or a different report format. If you want to cut and paste data from this web page into another application, such as a spreadsheet, select the comma-delimited format. Click on the Generate Report button once you have made your selections.

YearReport Format
Highlight with AQI colors
Area Monitoring Site POC Highest Second Highest Third Highest Fourth Highest
Date Time Value Date Time Value Date Time Value Date Time Value
Dallas-Fort Worth
Ft. Worth Northwest C13/AH302 201/14/202111003901/18/202110003801/17/202111003801/15/2021090037
Keller C17201/18/202112003901/17/202110003501/15/202110003501/14/2021100035
Frisco C31/C680101/18/202111004001/04/202110003901/14/202111003801/15/2021100037
Midlothian OFW C52/A137101/18/202112004201/05/202111004001/03/202110003901/17/2021110038
Denton Airport South C56/A163/X157101/14/202110004001/15/202110003901/13/202109003801/18/2021100037
Arlington Municipal Airport C61101/18/202111004201/03/202110003801/17/202110003701/15/2021100037
Dallas North No.2 C63/C679101/18/202112003701/15/202110003601/14/202110003601/05/2021130036
Rockwall Heath C69101/18/202110003801/04/202110003601/14/202112003501/05/2021110035
Grapevine Fairway C70/A301/X182101/14/202111003601/18/202111003401/15/202110003401/17/2021120033
Kaufman C71/A304/X071101/18/202111003801/04/202112003701/03/202112003601/05/2021120034
Granbury C73/C681101/18/202110003901/14/202111003701/05/202112003701/15/2021090036
Eagle Mountain Lake C75 101/18/202110004001/14/202110004001/04/202110004001/15/2021100039
Parker County C76101/05/202113004301/18/202111004101/04/202112004101/14/2021110039
Cleburne Airport C77/C682101/18/202113004401/05/202111004101/17/202111003901/03/2021100039
Dallas Hinton St. C401/C60/AH161 301/18/202112003501/14/202111003501/15/202110003401/03/2021100033
Dallas Executive Airport C402101/18/202110004101/14/202111003901/03/202110003901/17/2021110038
Greenville C1006/A198101/18/202110004301/04/202110004101/14/202112003801/15/2021100036
Pilot Point C1032101/14/202111003901/04/202111003901/15/202110003801/17/2021110036
Italy C1044/A323101/18/202111004101/03/202110004101/05/202111004001/04/2021110038
Corsicana Airport C1051101/03/202110004301/18/202113004201/05/202111004001/04/2021120039
Tyler-Longview-Marshall
Longview C19/A127/C644201/18/202112004701/03/202110004101/04/202110003901/14/2021110038
Tyler Airport Relocated C82101/18/202112004901/03/202111004601/04/202112004501/05/2021100040
Karnack C85/AFHP303101/18/202111004401/03/202110003801/15/202111003601/14/2021100036
El Paso-Juarez
El Paso UTEP C12/A125/X151/G125201/02/202110003601/03/202109003501/23/202110003401/22/2021100034
Ascarate Park SE C37/A332/A172/X159101/06/202108003601/03/202109003101/19/202109003001/16/2021120030
Chamizal C41/AH126 101/06/202109003901/02/202110003801/03/202110003701/22/2021100035
Socorro Hueco C49/F312101/17/202111003601/23/202110003501/09/202110003501/19/2021090034
Skyline Park C72101/06/202108004301/03/202116004201/15/202108004001/02/2021120040
Ivanhoe C414/F514101/06/202109003901/23/202110003701/15/202109003701/22/2021100033
Waco
Waco Mazanec C1037101/05/202113004701/03/202111004601/18/202111004401/04/2021120042
Temple Georgia C1045101/05/202112004901/18/202111004601/03/202111004601/17/2021100040
Killeen Skylark Field C1047101/05/202111004401/03/202110004201/04/202111003701/02/2021100037
Beaumont-Port Arthur
Beaumont-Downtown C2/A112/C2002 201/18/202112004601/04/202110004601/19/202109004501/03/2021100045
West Orange C9/A141201/18/202111004501/04/202109004401/03/202110004401/19/2021090043
Port Arthur West C28/A128/A228101/04/202110004701/18/202112004601/03/202110004601/19/2021100044
Hamshire C64/C654101/18/202111004701/19/202109004601/04/202110004601/14/2021100045
SETRPC 40 Sabine Pass C640/C1654101/19/202110004601/18/202112004601/04/202110004501/03/2021090045
SETRPC Mauriceville 42 C642/C311/C6651 N01/14/202111005301/19/202110005101/04/202110005101/18/2021130050
SETRPC 43 Jefferson Co Airport C643101/04/202110004801/18/202112004701/03/202110004601/19/2021080044
Nederland High School C1035 101/18/202111004601/19/202109004501/03/202110004501/14/2021100044
Austin
Austin North Hills Drive C3/A322201/03/202110004401/18/202111004201/17/202110004101/05/2021100041
Audubon C38101/17/202110004301/03/202110004301/18/202110004201/04/2021100042
Houston-Galveston-Brazoria
Houston East C1/G316201/03/202110004401/19/202109004301/14/202110004101/04/2021100041
Houston Aldine C8/AF108/X150 201/17/202110004401/14/202110004401/03/202110004401/19/2021100043
Channelview C15/AH115 301/14/202111004301/03/202110004301/17/202111004201/04/2021100040
Northwest Harris Co. C26/A110/X154201/03/202111004301/19/202110004101/05/202111004101/18/2021110040
Hou.DeerPrk2 C35/235/1001/AFH139FP239101/19/202107004501/14/202110004501/04/202110004501/17/2021100043
Seabrook Friendship Park C45101/19/202108003901/14/202110003901/03/202110003901/17/2021100038
Houston Bayland Park C53/A146 101/19/202109004601/18/202110004601/05/202110004501/03/2021100045
Conroe Relocated C78/A321101/05/202111005101/18/202111004701/03/202111004601/17/2021110042
Manvel Croix Park C84101/18/202110004501/05/202111004501/19/202109004401/17/2021100044
Clinton C403/C304/AH113 301/03/202109004101/17/202110003801/05/202111003801/06/2021090036
Houston North Wayside C405101/03/202110003801/19/202109003701/17/202110003401/06/2021090033
Houston Monroe C406101/14/202110003901/19/202108003801/18/202110003801/17/2021100038
Lang C408201/03/202110004501/19/202110004401/17/202110004301/14/2021100041
Houston Croquet C409201/18/202111004401/05/202111004401/03/202110004301/19/2021080042
Houston Westhollow C410/C3003101/05/202112004101/18/202110003801/03/202110003801/19/2021090037
Park Place C416101/03/202110004301/14/202110004201/19/202108004101/18/2021100041
Sheldon C5511 N01/04/202115004901/03/202112004101/01/202122003901/19/2021090038
Baytown Wetlands Center C5521 N01/18/202111004101/19/202108003901/17/202111003901/14/2021100038
Crosby Library C5531 N01/03/202110004101/04/202110003901/02/202110003601/14/2021110035
West Houston C5541 N01/05/202111003901/03/202110003901/17/202110003701/18/2021100036
La Porte Sylvan Beach C5561 N01/17/202110004301/14/202110004301/05/202114004201/03/2021090042
Mercer Arboretum C5571 N01/18/202112004001/17/202110004001/03/202110004001/14/2021100039
Tom Bass C5581 N01/18/202111004601/19/202109004501/05/202110004301/17/2021100042
Katy Park C5591 N01/05/202112004701/03/202111004401/17/202110004201/19/2021110041
Atascocita C5601 N01/18/202112004001/17/202110004001/03/202110003901/19/2021100038
Meyer Park C5611 N01/03/202111004401/19/202110004301/17/202110004201/14/2021100041
Bunker Hill Village C5621 N01/19/202110003901/18/202110003901/03/202110003901/17/2021100038
Huffman Wolf Road C5631 N01/18/202111004801/19/202110004701/14/202111004501/03/2021100045
Wallisville Road C617 1 N01/19/202109004801/18/202111004801/14/202111004801/03/2021090047
Texas City 34th St. C620 1 N01/19/202107005101/05/202120005101/18/202120005001/14/2021100050
UH Moody Tower C6951 N01/19/202110004501/17/202111004501/14/202110004401/04/2021110044
UH WG Jones Forest C6981 N01/03/202112005201/05/202112005101/18/202113004901/19/2021110048
UH West Liberty C6991 N01/19/202109004401/18/202111004401/14/202111004201/17/2021120041
Lynchburg Ferry C1015/A165 101/03/202110004301/14/202110003801/18/202111003601/19/2021080034
Lake Jackson C1016 101/05/202111004801/19/202109004401/18/202110004401/14/2021110044
Baytown Garth C1017101/18/202111004701/19/202108004601/03/202110004501/14/2021100044
Galveston 99th St. C1034/A320/X183101/05/202120005501/06/202101005101/18/202112005001/03/2021120050
Oyster Creek C1607 1 N01/05/202112005701/18/202109005501/19/202109005301/03/2021100051
San Antonio
San Antonio Northwest C23201/03/202110004801/17/202110004601/04/202110004301/02/2021110040
Camp Bullis C58 101/03/202110005401/17/202110005101/04/202110005001/16/2021100044
Calaveras Lake C59101/03/202111004801/17/202111004701/04/202110004301/18/2021120040
Heritage Middle School C6221 N01/03/202112005001/17/202110004701/04/202112004701/13/2021120041
Corpus Christi-Victoria
Corpus Christi West C4201/14/202111004301/03/202111004301/19/202107004101/17/2021100041
Corpus Christi Tuloso C21101/14/202111004501/03/202111004401/17/202111004301/19/2021090042
Victoria C87101/17/202111004801/03/202110004601/19/202110004501/18/2021100043
Lower Rio Grande Valley
Mission C43/AP143101/04/202110004501/17/202112004301/16/202110004201/14/2021100040
Harlingen Teege C1023101/16/202111004101/17/202110004001/03/202110004001/02/2021110039
Laredo
Laredo Vidaurri C44/AFGP144/P244101/17/202110004401/16/202113004301/03/202110004301/01/2021100041
POC (Parameter Occurrence Code): a code used to correctly separate data from multiple instruments at one site.
 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.