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Four Highest Eight-Hour Ozone Concentrations in 2021
as of April 13

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 204/12/202112005904/11/202111005903/04/202111005704/08/2021110056
Keller C17204/12/202112005804/11/202112005603/04/202112005604/01/2021120055
Frisco C31/C680104/12/202112006603/04/202112006204/11/202111005904/08/2021120059
Midlothian OFW C52/A137104/13/202112005904/01/202111005803/04/202111005804/11/2021130057
Denton Airport South C56/A163/X157104/12/202112006504/11/202111006203/04/202111006204/08/2021120061
Arlington Municipal Airport C61103/04/202112006004/11/202111005804/13/202112005704/01/2021110056
Dallas North No.2 C63/C679103/04/202112006104/12/202113005604/08/202113005603/08/2021100056
Rockwall Heath C69103/04/202111005903/08/202111005704/12/202111005204/08/2021100052
Grapevine Fairway C70/A301/X182104/12/202112005803/04/202112005704/01/202112005304/11/2021110052
Kaufman C71/A304/X071104/01/202111005404/12/202111005304/08/202111005303/29/2021110053
Granbury C73/C681104/01/202111005804/11/202112005704/02/202112005703/04/2021140057
Eagle Mountain Lake C75 104/12/202111006404/11/202112006203/04/202112006203/08/2021110059
Parker County C76103/26/202118006004/11/202112005904/02/202110005904/01/2021120059
Cleburne Airport C77/C682104/13/202112006104/11/202112006103/04/202111006004/01/2021120059
Dallas Hinton St. C401/C60/AH161 304/01/202112005603/04/202111005604/13/202112005504/11/2021110054
Dallas Executive Airport C402104/13/202111006003/04/202111005904/01/202111005804/11/2021110057
Greenville C1006/A198103/04/202110005904/12/202110005603/08/202110005604/08/2021100054
Pilot Point C1032104/11/202111006304/12/202112006103/04/202112006104/08/2021120060
Italy C1044/A323103/04/202111005604/13/202112005504/01/202111005504/11/2021110054
Corsicana Airport C1051103/04/202111006204/12/202110005403/26/202111005403/08/2021100054
Tyler-Longview-Marshall
Longview C19/A127/C644204/13/202111005803/08/202110005602/23/202114005604/08/2021100052
Tyler Airport Relocated C82103/04/202111006104/08/202111005803/08/202110005804/13/2021100057
Karnack C85/AFHP303104/11/202110005704/08/202109005502/23/202111005503/08/2021110054
El Paso-Juarez
El Paso UTEP C12/A125/X151/G125204/04/202110006103/07/202111006003/28/202111005804/02/2021110057
Ascarate Park SE C37/A332/A172/X159103/28/202111005304/10/202110005203/07/202110005204/04/2021100051
Chamizal C41/AH126 103/07/202111005804/04/202110005703/16/202116005404/10/2021100053
Socorro Hueco C49/F312104/10/202110005704/09/202109005604/07/202110005504/04/2021110055
Skyline Park C72103/16/202116005703/07/202111005704/04/202111005603/28/2021110055
Ivanhoe C414/F514103/16/202116005904/10/202110005603/22/202113005604/06/2021160055
Ojo De Agua C1021/FG121/FG221104/04/202110006403/28/202111006404/03/202110006104/02/2021110060
Waco
Waco Mazanec C1037104/11/202111005903/04/202111005903/26/202111005804/02/2021150057
Temple Georgia C1045104/02/202114006303/26/202112006304/11/202111006203/04/2021120062
Killeen Skylark Field C1047104/11/202112007003/26/202113006403/04/202111006004/08/2021110057
Beaumont-Port Arthur
Beaumont-Downtown C2/A112/C2002 204/12/202110005603/07/202111005503/08/202111005404/04/2021090053
West Orange C9/A141203/08/202110005404/12/202111005304/08/202109005303/23/2021100052
Port Arthur West C28/A128/A228104/12/202111005603/08/202111005504/11/202111005403/07/2021110053
Hamshire C64/C654104/11/202111005903/08/202111005604/12/202110005504/02/2021110053
SETRPC Port Arthur C6281 N03/08/202111005603/09/202109005403/07/202110005303/23/2021110050
SETRPC 40 Sabine Pass C640/C1654103/08/202111005404/12/202113005304/02/202110005204/05/2021080051
SETRPC Mauriceville 42 C642/C311/C6651 N04/08/202110005803/08/202110005804/04/202109005703/07/2021110057
SETRPC 43 Jefferson Co Airport C643103/08/202111005603/07/202111005604/11/202110005404/12/2021110053
Nederland High School C1035 103/07/202111005603/08/202111005504/11/202111005404/12/2021100053
Austin
Austin North Hills Drive C3/A322204/11/202112006503/26/202112006004/02/202110005704/10/2021110054
Audubon C38104/11/202111006504/02/202109005803/26/202111005704/01/2021110054
Dripping Springs School C6141 N04/11/202112007104/02/202110006104/10/202111005604/01/2021110056
CAPCOG Lake Georgetown C6901 N04/11/202111006103/26/202112005904/02/202111005503/29/2021110052
Lockhart C16041 N04/11/202111006303/26/202112006104/10/202111005804/02/2021090056
St. Edwards University C16051 N04/11/202112006003/26/202111005404/02/202110005304/10/2021110052
CAPCOG Bastrop CAMS16121 N03/26/202113006504/11/202113005203/21/202111005203/23/2021110051
CAPCOG Elgin C16131 N03/26/202111005404/11/202111005304/02/202112005204/10/2021110050
CAPCOG East Austin C16191 N04/11/202111006004/02/202110005403/26/202111005404/10/2021110051
CAPCOG Round Rock Brushy Creek W C16201 N04/11/202111005903/26/202111005404/02/202110005304/01/2021110049
CAPCOG San Marcos Staples Road C16751 N04/11/202111006003/03/202112006003/04/202111005703/26/2021110056
Houston-Galveston-Brazoria
Houston East C1/G316204/11/202110007604/12/202109005602/23/202110005504/08/2021090053
Houston Aldine C8/AF108/X150 204/11/202111008604/12/202110006204/04/202110005803/21/2021110058
Channelview C15/AH115 304/11/202110006203/17/202111005204/10/202112005104/02/2021110051
Northwest Harris Co. C26/A110/X154204/11/202112007003/26/202110006204/12/202109006103/21/2021110059
Hou.DeerPrk2 C35/235/1001/AFH139FP239104/11/202111006104/12/202110005504/10/202111005304/02/2021110053
Seabrook Friendship Park C45103/23/202111005704/11/202111005103/07/202113004903/25/2021110048
Houston Bayland Park C53/A146 104/11/202110006604/01/202112005604/10/202112005504/02/2021110055
Conroe Relocated C78/A321104/12/202110007304/08/202111007003/04/202110006103/08/2021100059
Manvel Croix Park C84104/02/202110005304/01/202111005302/23/202110005304/04/2021090052
Clinton C403/C304/AH113 304/11/202110007004/01/202111005304/10/202111005204/12/2021110051
Houston North Wayside C405104/11/202111007504/12/202110005104/02/202110005003/07/2021100049
Houston Monroe C406104/11/202110006103/08/202110005304/03/202111005203/17/2021110052
Lang C408204/11/202111008904/08/202110005704/02/202111005503/26/2021100055
Houston Croquet C409204/11/202111005703/03/202111005603/08/202110005102/23/2021100050
Houston Westhollow C410/C3003104/11/202111006203/26/202110005304/02/202110005004/10/2021110049
Park Place C416104/11/202111007203/03/202111005904/02/202110005404/12/2021110053
Houston Harvard Street C417104/11/202111007804/02/202110005204/08/202109005104/12/2021090050
Sheldon C5511 N04/11/202112005604/12/202111005104/02/202112005103/08/2021110051
Baytown Wetlands Center C5521 N04/11/202111005104/02/202110004804/01/202111004803/08/2021110048
Crosby Library C5531 N04/11/202112006104/12/202109005004/02/202110005003/07/2021110050
West Houston C5541 N04/11/202111006704/02/202110005103/26/202110005104/10/2021120050
La Porte Sylvan Beach C5561 N03/23/202112005804/12/202111005104/11/202111005104/02/2021130051
Mercer Arboretum C5571 N04/12/202110005904/11/202111005603/21/202111005604/08/2021110055
Tom Bass C5581 N04/11/202111006204/10/202111005503/08/202111005402/23/2021100053
Katy Park C5591 N03/26/202110005603/08/202111005203/21/202111005103/07/2021100051
Atascocita C5601 N04/11/202111005504/08/202109005504/12/202110005204/02/2021100049
Meyer Park C5611 N04/11/202112007104/12/202110006203/21/202111006003/26/2021100059
Bunker Hill Village C5621 N04/11/202111006804/10/202111005104/02/202111005104/01/2021110050
Huffman Wolf Road C5631 N02/23/202110005803/07/202111005704/12/202109005504/02/2021110055
Wallisville Road C617 1 N04/11/202110006203/17/202111005604/12/202109005403/23/2021110054
Texas City 34th St. C620 1 N03/23/202111007404/11/202110006304/12/202110006204/03/2021100062
UH Moody Tower C6951 N04/11/202110007403/03/202113005502/23/202110005404/10/2021110053
UH WG Jones Forest C6981 N04/12/202110007103/04/202111006904/08/202111006702/23/2021110061
UH West Liberty C6991 N01/19/202109004401/18/202111004401/14/202111004202/03/2021100041
Lynchburg Ferry C1015/A165 104/11/202110005504/02/202111005104/12/202112004904/03/2021110049
Lake Jackson C1016 104/01/202111006004/10/202111005804/02/202110005804/03/2021100057
Baytown Garth C1017104/11/202111006304/12/202109005603/23/202111005403/17/2021110054
Galveston 99th St. C1034/A320/X183104/03/202110006004/01/202111005803/07/202113005804/02/2021140057
UH Smith Point C16061 N04/12/202110005404/11/202111005404/03/202110005104/02/2021110051
Oyster Creek C1607 1 N03/08/202110006203/19/202112006103/07/202112006103/03/2021100061
UH Launch Trailer C16111 N04/11/202111007604/02/202110005604/04/202110005404/10/2021110053
San Antonio
San Antonio Northwest C23204/11/202111007203/26/202111006704/02/202110006503/21/2021100059
Camp Bullis C58 104/11/202111007603/26/202112006904/02/202110006803/21/2021100062
Calaveras Lake C59104/11/202111006703/26/202111006404/10/202111006004/02/2021090059
Elm Creek Elementary C5011 N04/11/202111006303/26/202111005904/02/202109005804/10/2021110055
Fair Oaks Ranch C5021 N04/11/202111006304/02/202110006003/26/202111006003/21/2021100056
Bulverde Elementary C5031 N04/11/202111007203/26/202112005704/10/202110005104/08/2021110050
New Braunfels Airport C5041 N04/11/202111006203/26/202111005704/02/202109005604/10/2021110053
City of Garden Ridge C5051 N04/11/202111006703/26/202111005904/02/202110005704/10/2021110053
Seguin Outdoor Learning Center C5061 N04/11/202111006003/26/202111006004/02/202109005703/21/2021110051
Heritage Middle School C6221 N04/11/202111006303/26/202111006004/10/202111005704/02/2021090057
CPS Pecan Valley C6781 N04/11/202111005803/26/202111005204/02/202109005104/10/2021110048
Government Canyon C16101 N04/11/202111006004/02/202110005703/26/202111005703/21/2021100052
Corpus Christi-Victoria
Corpus Christi West C4203/26/202111005904/01/202118005604/10/202113005403/17/2021100054
Corpus Christi Tuloso C21104/10/202113005603/26/202111005603/17/202110005604/01/2021120054
Victoria C87104/11/202110005904/10/202111005604/01/202111005503/17/2021100053
Lower Rio Grande Valley
Mission C43/AP143103/20/202110005704/02/202109005404/08/202110005203/21/2021090052
Harlingen Teege C1023103/20/202110005303/17/202111005304/02/202109005203/25/2021110051
Laredo
Laredo Vidaurri C44/AFGP144/P244104/10/202112006004/11/202110005703/20/202110005504/02/2021090054
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.