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Four Highest Eight-Hour Ozone Concentrations in 2025
as of April 28

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 2025 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 204/10/202511007203/01/202512007004/12/202512006804/09/2025120065
Keller C17203/01/202511007204/12/202514006704/10/202512006704/09/2025130061
Frisco C31/C680104/09/202511006804/10/202511006304/12/202512006203/25/2025110062
Denton Airport South C56/A163/X157104/12/202512006204/22/202511006104/09/202512006003/25/2025110059
Arlington Municipal Airport C61104/10/202511007004/12/202515006704/09/202512006603/01/2025120062
Dallas North No.2 C63/C679104/09/202511006704/12/202515006204/13/202511006104/10/2025120061
Rockwall Heath C69104/08/202512005804/07/202511005704/09/202511005604/10/2025120054
Grapevine Fairway C70/A301/X182104/10/202511006704/12/202514006404/09/202511006304/13/2025110061
Kaufman C71/A304/X071104/09/202511006704/08/202511006704/07/202511006703/01/2025100061
Granbury C73/C681104/10/202512007604/12/202512006904/15/202512006303/02/2025100063
Eagle Mountain Lake C75 104/12/202513006803/01/202511006804/10/202512006504/09/2025140063
Parker County C76104/10/202511006804/12/202514006603/01/202512006404/21/2025110061
Cleburne Airport C77/C682104/10/202512007104/12/202512006704/09/202512006403/02/2025100064
Dallas Hinton St. C401/C60/AH161 302/02/202512005402/03/202511004202/01/202509004201/13/2025100040
Dallas Executive Airport C402104/09/202511006904/10/202511006804/12/202515006503/01/2025110065
Greenville C1006/A198104/09/202511006504/10/202511005904/16/202510005804/22/2025100057
Pilot Point C1032104/09/202512006903/25/202511006904/22/202511006804/12/2025120066
Italy C1044/A323104/12/202515006404/09/202511006404/08/202510006404/07/2025110060
Corsicana Airport C1051104/09/202511007004/12/202513006803/01/202511006804/07/2025120067
Tyler-Longview-Marshall
Longview C19/A127/C644204/09/202513007504/08/202510006704/13/202513006203/17/2025150061
Tyler Airport Relocated C82104/09/202515006804/08/202510006603/01/202510006404/16/2025120061
Karnack C85/AFHP303104/09/202511006602/28/202510005904/08/202510005804/13/2025120057
El Paso-Juarez
Ascarate Park SE C37/A332/A172/X159104/13/202511005804/11/202510005704/21/202510005404/19/2025130052
Chamizal C41/AH126 104/13/202511006304/12/202512005603/02/202509005604/19/2025120053
Socorro Hueco C49/F312104/13/202510006004/21/202510005604/11/202510005604/25/2025100053
Skyline Park C72104/11/202509006604/13/202512006504/21/202510006103/30/2025160059
Ivanhoe C414/F514104/21/202510005204/13/202511005204/11/202510004904/12/2025110048
Ojo De Agua C1021/FG121/FG221104/13/202511005704/11/202509005604/10/202521005504/21/2025110052
Waco
Waco Mazanec C1037104/09/202511007204/10/202511006904/08/202510006904/14/2025110064
Temple Georgia C1045104/09/202511007004/12/202511006804/10/202511006604/08/2025110063
Killeen Skylark Field C1047104/12/202511007404/09/202511007104/10/202513006704/14/2025120065
Beaumont-Port Arthur
Beaumont-Downtown C2/A112/C2002 203/25/202510006104/16/202510005804/12/202510005604/10/2025090056
West Orange C9/A141204/10/202509005703/17/202511005703/01/202511005704/16/2025100055
Port Arthur West C28/A128/A228103/01/202511005703/17/202511005404/16/202509005204/09/2025100052
Hamshire C64/C654103/01/202512006404/16/202510005903/17/202510005804/10/2025090057
SETRPC Port Arthur C6281 N03/01/202512006403/17/202511005903/11/202509005302/02/2025100053
SETRPC 40 Sabine Pass C640/C1654103/01/202512006803/17/202510006004/08/202511005903/10/2025120059
SETRPC Mauriceville 42 C642/C311/C6651 N03/01/202510005603/17/202511005503/11/202510005402/28/2025110051
SETRPC 43 Jefferson Co Airport C643103/01/202511006004/08/202509005603/17/202511005604/16/2025090054
Nederland 17th Street C1035103/01/202516006303/25/202510006104/10/202509005703/17/2025110057
Austin
Austin North Hills Drive C3/A322204/10/202511006504/12/202510006304/21/202511006104/11/2025110061
Audubon C38104/09/202510006604/12/202510006504/10/202511006404/11/2025100063
Dripping Springs School C6141 N04/11/202511007704/09/202511007704/08/202512007604/21/2025110075
Lockhart C16041 N04/09/202512007404/08/202510007104/12/202511006704/11/2025110067
St. Edwards University C16051 N04/11/202511007104/08/202511007104/09/202511007004/12/2025110068
CAPCOG Bastrop CAMS16121 N04/09/202511006504/21/202511006404/12/202510006404/08/2025100064
CAPCOG Elgin C16131 N04/08/202510006603/01/202511006604/09/202512006504/11/2025100063
CAPCOG East Austin C16191 N04/12/202511006204/11/202510006204/09/202511006204/08/2025110062
CAPCOG Round Rock Brushy Creek W C16201 N04/10/202511006604/09/202510006404/12/202510006304/08/2025110062
CAPCOG Taylor Murphy Park C16291 N04/09/202511007804/12/202509007704/08/202510007704/10/2025110075
CAPCOG Lake Kyle Park C16301 N04/11/202511006504/08/202511006504/12/202511006404/09/2025110063
CAPCOG San Marcos Staples Road C16751 N04/11/202511007004/12/202512006604/03/202512006604/04/2025110065
Houston-Galveston-Brazoria
Houston East C1/G316203/25/202510007604/12/202511006303/01/202511006204/10/2025090061
Houston Aldine C8/AF108/X150 203/25/202510008104/12/202510007104/09/202510007004/10/2025100069
Channelview C15/AH115 303/25/202509006204/08/202511006004/10/202508005804/09/2025100058
Northwest Harris Co. C26/A110/X154203/25/202512007704/09/202510007604/12/202511007404/10/2025100071
Hou.DeerPrk2 C35/235/1001/AFH139FP239103/01/202511006603/24/202511006304/08/202511006204/12/2025110060
Seabrook Friendship Park C45103/01/202512006804/08/202512006004/11/202511005703/24/2025110056
Houston Bayland Park C53/A146 103/25/202511006804/11/202511006703/24/202512006504/12/2025100064
Conroe Relocated C78/A321104/12/202511008004/10/202511008004/09/202510007803/25/2025110076
Manvel Croix Park C84103/01/202511006904/11/202511006603/24/202512006204/12/2025100059
Clinton C403/C304/AH113 303/01/202511006004/08/202511005704/12/202510005604/11/2025100056
Houston North Wayside C405/C1033103/25/202510006704/12/202511005704/09/202509005704/16/2025100053
Houston Monroe C406103/01/202511006103/24/202512006004/08/202511005703/25/2025110057
Lang C408203/25/202511007504/09/202510006404/12/202510006204/10/2025100062
Houston Croquet C409203/01/202511007004/11/202511006604/09/202510006504/12/2025100064
Houston Westhollow C410/C3003103/01/202512006504/11/202510006304/09/202510006303/25/2025100063
Park Place C416103/25/202511006503/01/202511006503/24/202511006304/12/2025110060
Houston Harvard Street C417103/25/202511007203/24/202512006404/09/202510006103/01/2025110061
Sheldon C5511 N03/25/202509006904/10/202508005903/01/202511005904/08/2025100058
Baytown Wetlands Center C5521 N03/01/202510006104/08/202512005702/01/202511005604/16/2025090055
Crosby Library C5531 N04/10/202508007104/12/202509005903/01/202510005904/16/2025090058
West Houston C5541 N03/25/202510007404/09/202509007204/12/202509007003/01/2025110070
La Porte Sylvan Beach C5561 N03/01/202512006004/08/202513005904/16/202509005504/09/2025090054
Mercer Arboretum C5571 N03/25/202510008604/10/202509007904/09/202510007804/12/2025090077
Tom Bass C5581 N03/01/202512007704/11/202510006804/12/202509006604/09/2025090066
Katy Park C5591 N04/09/202509006404/12/202509006004/11/202509005904/10/2025090058
Atascocita C5601 N03/25/202509007104/12/202509006604/09/202509006504/10/2025090064
Meyer Park C5611 N03/25/202510008504/10/202510007504/12/202509007404/09/2025090073
Bunker Hill Village C5621 N03/25/202510006904/12/202510006704/09/202509006703/01/2025110067
Huffman Wolf Road C5631 N03/25/202510008004/10/202509007404/09/202509006704/12/2025090064
HRM-3 Haden Road C603/A114 1 N03/01/202510006303/17/202510005403/21/202509005203/13/2025110050
Wallisville Road C617 1 N03/01/202510005603/17/202510005102/01/202511004803/21/2025090047
Texas City 34th St. C620 1 N03/01/202512007503/17/202510005603/16/202511005402/01/2025110053
Lynchburg Ferry C1015/A165 103/17/202510006004/09/202509005803/01/202510005804/16/2025090057
Lake Jackson C1016 103/01/202511006704/11/202511006604/08/202511006103/24/2025120061
Baytown Garth C1017103/25/202510007104/10/202508006404/16/202510005904/12/2025110059
Galveston 99th St. C1034/A320/X183103/01/202516009702/01/202512008204/11/202512006603/24/2025130063
Oyster Creek C1607 1 N04/11/202511006803/24/202511006404/08/202511006204/12/2025090060
San Antonio
San Antonio Northwest C23204/21/202511006404/11/202512006404/12/202511006004/10/2025110059
Camp Bullis C58 104/11/202511007504/10/202511007004/21/202511006904/12/2025110069
Calaveras Lake C59104/11/202511006804/12/202511006604/08/202510006504/21/2025100064
Elm Creek Elementary C5011 N04/21/202511007104/11/202511007004/12/202510006404/08/2025100062
Fair Oaks Ranch C5021 N04/11/202512007204/10/202511007104/12/202510006804/21/2025110066
Bulverde Elementary C5031 N03/01/202511006104/10/202511005802/28/202511005804/12/2025100057
New Braunfels Airport C5041 N03/01/202510006502/28/202511006103/10/202512005403/02/2025090054
AACOG City of Garden Ridge C505 1 N04/11/202511007104/21/202512006804/12/202511006604/08/2025120062
Seguin Outdoor Learning Center C5061 N03/01/202511006602/28/202511006203/13/202512006004/11/2025120059
Heritage Middle School C6221 N04/21/202511007304/11/202511007204/08/202511006904/12/2025110067
CPS Pecan Valley C6781 N04/21/202511006204/11/202511006204/08/202511006004/12/2025110059
Government Canyon C16101 N04/21/202511007404/11/202511007404/12/202510006804/08/2025100066
Corpus Christi-Victoria
Corpus Christi West C4204/08/202510006704/09/202509005902/28/202512005804/12/2025100056
Corpus Christi Tuloso C21104/08/202510006604/09/202508006004/11/202511005902/28/2025120058
Victoria C87104/08/202509006504/09/202509006402/28/202513006304/11/2025130061
Lower Rio Grande Valley
Mission C43/AP143104/08/202510007104/09/202511005803/10/202511005804/11/2025100057
Harlingen Teege C1023104/08/202510006004/09/202510005704/12/202511005504/07/2025110055
Laredo
Laredo College C441 N04/08/202511006904/20/202512006204/12/202511006104/09/2025100061
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.