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Four Highest Eight-Hour Ozone Concentrations in 2021
as of July 23

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 206/16/2021110010206/15/202111009506/13/202112008007/21/2021110073
Keller C17206/16/2021110010006/19/202110007206/15/202110007206/13/2021130072
Frisco C31/C680106/17/202110008506/19/202110008206/16/202111008106/12/2021130067
Midlothian OFW C52/A137106/16/202109007206/19/202110006705/06/202111006407/21/2021100062
Denton Airport South C56/A163/X157106/16/202112009706/19/202111008506/17/202111007806/18/2021090076
Arlington Municipal Airport C61106/15/202111007606/16/202109007307/21/202111007106/19/2021100068
Dallas North No.2 C63/C679106/16/202110008806/17/202110007606/19/202110007307/01/2021100064
Rockwall Heath C69106/17/202109006606/16/202109006606/19/202110006303/04/2021110059
Grapevine Fairway C70/A301/X182106/16/202110009606/19/202110007207/07/202112006806/18/2021090066
Kaufman C71/A304/X071106/19/202110006506/02/202111005703/04/202110005706/16/2021090056
Granbury C73/C681106/15/202112007707/21/202111006606/16/202110006506/19/2021110059
Eagle Mountain Lake C75 106/16/2021120011407/07/202112007606/15/202113007406/18/2021110070
Parker County C76106/16/202113008106/15/202111006806/19/202110006205/19/2021100061
Cleburne Airport C77/C682106/15/202111007607/21/202111007505/06/202111007306/16/2021100068
Dallas Hinton St. C401/C60/AH161 306/16/202110009506/19/202110007606/17/202110007406/13/2021110074
Dallas Executive Airport C402106/16/202110007806/19/202111007006/13/202111007006/15/2021110068
Greenville C1006/A198106/19/202111006806/16/202109006103/04/202110005906/17/2021090056
Pilot Point C1032106/19/202111008906/17/202111008506/16/202111008507/22/2021100076
Italy C1044/A323106/19/202109006805/06/202111006406/16/202109006305/07/2021110060
Corsicana Airport C1051106/19/202110006705/07/202115006304/26/202113006203/04/2021110062
Tyler-Longview-Marshall
Longview C19/A127/C644206/17/202110006806/16/202110006306/18/202110006107/04/2021100060
Tyler Airport Relocated C82106/16/202110007006/18/202110006303/04/202111006107/04/2021110058
Karnack C85/AFHP303106/15/202109006006/17/202110005906/18/202109005804/11/2021100057
El Paso-Juarez
El Paso UTEP C12/A125/X151/G125207/09/202110008406/22/202111008007/21/202110007107/03/2021110071
Ascarate Park SE C37/A332/A172/X159107/09/202110006407/03/202111006205/05/202111006206/19/2021100060
Chamizal C41/AH126 107/09/202110007306/22/202111007305/05/202111006907/03/2021110067
Socorro Hueco C49/F312107/05/202111008107/17/202108007407/22/202110007107/09/2021100070
Skyline Park C72106/22/202111007405/05/202111006906/19/202110006807/22/2021100066
Ivanhoe C414/F514107/05/202111006905/05/202111006606/22/202111006207/22/2021100061
Ojo De Agua C1021/FG121/FG221106/22/202110007407/09/202110007105/05/202110007107/12/2021110067
Waco
Waco Mazanec C1037106/19/202109006805/06/202111006406/18/202111006305/07/2021100062
Temple Georgia C1045106/19/202110006706/16/202111006606/18/202111006404/02/2021140063
Killeen Skylark Field C1047104/11/202112007006/19/202110006906/16/202112006907/22/2021100066
Beaumont-Port Arthur
Beaumont-Downtown C2/A112/C2002 205/07/202110006506/17/202111006004/25/202110005906/15/2021090058
West Orange C9/A141206/17/202110006406/16/202110006305/07/202110006004/20/2021100060
Port Arthur West C28/A128/A228106/17/202112006606/16/202110006506/14/202110006206/15/2021080060
Hamshire C64/C654105/07/202109006306/18/202109006204/20/202110006104/11/2021110059
SETRPC Port Arthur C6281 N06/17/202112006806/16/202110006105/07/202109005904/20/2021100057
SETRPC 40 Sabine Pass C640/C1654106/17/202112006306/19/202110006106/16/202110006006/14/2021090059
SETRPC Mauriceville 42 C642/C311/C6651 N05/07/202110006806/17/202109006004/20/202110005904/25/2021110058
SETRPC 43 Jefferson Co Airport C643106/16/202110006706/15/202108006706/17/202111006305/07/2021090059
Nederland High School C1035 106/16/202110006806/15/202108006506/17/202111006405/07/2021100059
Austin
Austin North Hills Drive C3/A322206/18/202109006504/11/202112006505/02/202112006206/17/2021090061
Audubon C38104/11/202111006504/19/202112005905/07/202110005804/02/2021090058
Dripping Springs School C6141 N04/11/202112007106/18/202113006606/16/202112006605/06/2021110064
CAPCOG Lake Georgetown C6901 N05/07/202110006404/11/202111006103/26/202112005905/06/2021110058
Lockhart C16041 N04/11/202111006303/26/202112006106/18/202110006004/25/2021110059
St. Edwards University C16051 N04/11/202112006006/18/202109005606/17/202109005505/20/2021100054
CAPCOG Bastrop CAMS16121 N03/26/202113006505/07/202111005304/11/202113005203/21/2021110052
CAPCOG Elgin C16131 N06/18/202110006406/19/202109005606/17/202110005506/16/2021120055
CAPCOG East Austin C16191 N06/18/202110006104/11/202111006005/02/202111005806/17/2021100057
CAPCOG Round Rock Brushy Creek W C16201 N04/11/202111005905/07/202109005805/02/202112005806/19/2021090055
CAPCOG San Marcos Staples Road C16751 N04/11/202111006003/03/202112006006/18/202111005906/17/2021100057
Houston-Galveston-Brazoria
Houston East C1/G316205/29/202111008606/19/202109007604/11/202110007606/15/2021100074
Houston Aldine C8/AF108/X150 204/11/202111008606/19/202110007504/20/202110006507/02/2021100064
Channelview C15/AH115 305/29/202112009006/19/202109006606/15/202109006604/20/2021110062
Northwest Harris Co. C26/A110/X154204/11/202112007005/07/202110006606/18/202109006203/26/2021100062
Hou.DeerPrk2 C35/235/1001/AFH139FP239106/19/202109008905/29/202110007406/16/202110007204/20/2021100072
Seabrook Friendship Park C45106/19/202109007906/18/202110006006/17/202115005904/20/2021110059
Houston Bayland Park C53/A146 106/18/202111008606/17/202109007806/15/202109007806/16/2021100074
Conroe Relocated C78/A321104/12/202110007304/08/202111007005/07/202111006604/26/2021100065
Manvel Croix Park C84106/17/202110007206/16/202109007206/18/202109007104/20/2021100071
Clinton C403/C304/AH113 305/29/202111007506/19/202109007004/11/202110007006/15/2021090069
Houston North Wayside C405/C1033104/11/202111007506/19/202109007105/29/202111006506/15/2021090064
Houston Monroe C406104/20/202110007106/16/202110006806/15/202109006806/17/2021100065
Lang C408204/11/202111008906/15/202110007007/01/202111006706/19/2021090065
Houston Croquet C409206/17/202109008706/16/202110008506/18/202110008106/15/2021080076
Houston Westhollow C410/C3003106/18/202111008206/15/202109006806/17/202109006707/21/2021120062
Park Place C416106/18/202110007906/17/202109007806/16/202110007806/15/2021090078
Houston Harvard Street C417106/15/202109007904/11/202111007805/29/202111007606/19/2021090075
Sheldon C5511 N04/20/202111006306/19/202112005704/11/202112005607/02/2021100053
Baytown Wetlands Center C5521 N06/19/202109006704/20/202111006305/29/202111006106/17/2021110058
Crosby Library C5531 N04/20/202111006605/29/202112006404/11/202112006106/19/2021100054
West Houston C5541 N06/18/202109008106/15/202108007806/17/202109007605/14/2021120074
La Porte Sylvan Beach C5561 N06/19/202109008104/20/202112006206/14/202115006006/17/2021160059
Mercer Arboretum C5571 N06/19/202112006005/07/202110006004/12/202110005904/20/2021100058
Tom Bass C5581 N06/16/202110007606/17/202110007406/15/202109007004/20/2021100069
Katy Park C5591 N05/14/202112006205/07/202109005903/26/202110005607/21/2021110055
Atascocita C5601 N04/20/202110005604/11/202111005504/08/202109005505/07/2021100054
Meyer Park C5611 N04/11/202112007105/07/202110006404/12/202110006207/01/2021110060
Bunker Hill Village C5621 N06/18/202110007506/15/202108007306/17/202109007004/11/2021110068
Huffman Wolf Road C5631 N04/20/202110006502/23/202110005805/07/202109005703/07/2021110057
HRM-3 Haden Road C603/A114 1 N05/29/202111008904/11/202110007506/19/202109007304/20/2021110073
Wallisville Road C617 1 N05/29/202111007604/20/202111007306/17/202109006404/11/2021100062
Texas City 34th St. C620 1 N03/23/202111007404/20/202111007106/19/202109007006/18/2021070066
UH Moody Tower C6951 N06/15/202109008006/17/202109007606/18/202110007505/29/2021110074
UH WG Jones Forest C6981 N04/12/202110007105/07/202110007004/26/202110007003/04/2021110069
UH West Liberty C6991 N01/19/202109004401/18/202111004401/14/202111004202/03/2021100041
Lynchburg Ferry C1015/A165 105/29/202111007206/19/202109006504/20/202111006206/17/2021100061
Lake Jackson C1016 105/05/202111007006/17/202109006706/18/202108006606/16/2021100061
Baytown Garth C1017105/29/202111008104/20/202111007506/15/202109006906/17/2021090068
Galveston 99th St. C1034/A320/X183106/14/202111007705/06/202111006504/20/202111006406/17/2021150062
UH Smith Point C16061 N06/19/202109007706/14/202112006604/20/202111006406/17/2021140061
Oyster Creek C1607 1 N06/16/202111007006/17/202108006805/05/202112006805/19/2021010064
UH Launch Trailer C16111 N06/15/202109007804/11/202111007606/17/202109007505/29/2021110075
San Antonio
San Antonio Northwest C23204/11/202111007206/18/202109007005/06/202110006703/26/2021110067
Camp Bullis C58 104/11/202111007606/18/202110007305/07/202110007105/20/2021110070
Calaveras Lake C59104/11/202111006703/26/202111006405/07/202109006204/25/2021100060
Elm Creek Elementary C5011 N06/15/202110006906/18/202109006405/06/202110006304/11/2021110063
Fair Oaks Ranch C5021 N05/07/202110006304/11/202111006306/18/202111006004/25/2021110060
Bulverde Elementary C5031 N04/11/202111007204/25/202112006306/19/202109006006/18/2021120060
New Braunfels Airport C5041 N04/11/202111006206/18/202108005906/17/202110005703/26/2021110057
City of Garden Ridge C5051 N04/11/202111006706/18/202110006305/20/202109006006/17/2021090059
Seguin Outdoor Learning Center C5061 N04/11/202111006003/26/202111006005/02/202112005704/02/2021090057
Heritage Middle School C6221 N04/11/202111006304/25/202111006206/18/202108006105/07/2021100061
CPS Pecan Valley C6781 N04/11/202111005803/26/202111005206/18/202108005104/02/2021090051
Government Canyon C16101 N05/20/202111006706/18/202111006105/07/202110006005/06/2021110060
Corpus Christi-Victoria
Corpus Christi West C4206/17/202115006206/15/202110006006/18/202110005903/26/2021110059
Corpus Christi Tuloso C21106/15/202110006106/18/202111006006/17/202111006004/24/2021110060
Victoria C87106/18/202113006306/17/202110006106/15/202111005904/11/2021100059
Lower Rio Grande Valley
Mission C43/AP143105/20/202110006204/25/202110006206/18/202109006005/07/2021090059
Harlingen Teege C1023106/18/202109005403/20/202110005303/17/202111005304/02/2021090052
Laredo
Laredo Vidaurri C44/AFGP144/P244105/03/202111006905/20/202111006106/18/202108006005/06/2021090060
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.