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Four Highest Eight-Hour Ozone Concentrations in 2020
as of February 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 2020 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 201/08/202010004202/02/202019004101/25/202011004102/16/2020110040
Keller C17201/08/202011004302/16/202011004002/15/202011004002/22/2020120038
Frisco C31/C680102/16/202013004501/08/202011004502/02/202014004202/15/2020110041
Midlothian OFW C52/A137101/08/202011004501/25/202011004302/02/202013004202/15/2020110040
Denton Airport South C56/A163/X157101/08/202011004602/16/202011004302/15/202011004302/02/2020100042
Arlington Municipal Airport C61102/15/202011003802/02/202014003801/08/202011003802/08/2020110037
Dallas North No.2 C63/C679101/08/202012004402/16/202012004302/02/202013004201/25/2020120041
Rockwall Heath C69101/08/202011004402/02/202013004201/25/202013004202/21/2020110041
Grapevine Fairway C70/A301/X182102/15/202011004101/08/202010004002/06/202011003902/16/2020110038
Kaufman C71/A304/X071101/08/202012004702/16/202012004202/02/202012004201/25/2020120042
Granbury C73/C681101/08/202010004402/16/202011004102/22/202015004002/15/2020100040
Eagle Mountain Lake C75 101/08/202011004702/16/202011004402/15/202010004202/02/2020110042
Parker County C76101/08/202011004801/27/202011004702/16/202013004401/26/2020140043
Cleburne Airport C77/C682101/08/202011004902/22/202014004402/16/202012004302/02/2020110042
Dallas Hinton St. C401/C60/AH161 301/08/202011004002/15/202011003902/16/202011003802/02/2020140038
Dallas Executive Airport C402101/08/202010004502/15/202011004402/02/202016004301/25/2020110042
Greenville C1006/A198101/08/202011004502/16/202012004102/02/202011004101/25/2020120041
Pilot Point C1032101/25/202014004502/16/202012004402/15/202012004402/02/2020100043
Italy C1044/A323101/08/202011004502/16/202011004102/02/202011004101/25/2020110041
Corsicana Airport C1051101/08/202012004502/02/202012004302/16/202011004201/25/2020110042
Tyler-Longview-Marshall
Longview C19/A127/C644202/02/202011004301/05/202011004301/06/202011004202/07/2020110041
Tyler Airport Relocated C82102/02/202019004601/08/202011004601/05/202011004501/06/2020110043
Karnack C85/AFHP303102/02/202010004701/08/202012004501/06/202010004201/05/2020100042
El Paso-Juarez
El Paso UTEP C12/A125/X151/G125202/23/202010004302/16/202010004101/19/202009004102/15/2020100040
Ascarate Park SE C37/A332/A172/X159102/23/202012004302/16/202010003901/30/202009003901/19/2020100039
Chamizal C41/AH126 102/23/202010005002/16/202010004902/15/202010004802/17/2020080045
Socorro Hueco C49/F312102/23/202010004402/16/202010004302/13/202010004302/15/2020100042
Skyline Park C72102/23/202010004602/17/202009004602/16/202010004602/15/2020110046
Ivanhoe C414/F514102/23/202011004702/16/202010004402/15/202011004401/27/2020120043
Waco
Waco Mazanec C1037101/08/202012005002/02/202012004501/05/202011004302/22/2020120042
Temple Georgia C1045102/02/202012004501/08/202011004502/22/202012004401/05/2020110042
Killeen Skylark Field C1047102/22/202013004701/08/202011004601/26/202011004402/02/2020110043
Beaumont-Port Arthur
Beaumont-Downtown C2/A112/C2002 202/02/202011005002/22/202011004402/08/202011004402/03/2020100044
West Orange C9/A141202/02/202010004802/08/202012004502/22/202011004402/03/2020090043
Port Arthur West C28/A128/A228102/02/202011004802/08/202011004602/07/202010004202/03/2020090042
Hamshire C64/C654102/02/202011004902/08/202011004602/22/202010004402/03/2020090044
SETRPC Port Arthur C6281 N02/02/202010004802/08/202010004502/07/202010004502/03/2020080043
SETRPC 40 Sabine Pass C640/C1654102/02/202011004802/16/202010004502/08/202012004402/22/2020120043
SETRPC Mauriceville 42 C642/C311/C6651 N02/02/202011005802/22/202011005302/08/202012005102/07/2020100049
SETRPC 43 Jefferson Co Airport C643102/02/202010005102/08/202012005002/03/202009004602/22/2020130045
Nederland High School C1035 102/02/202011004902/08/202011004402/03/202009004402/22/2020130042
Austin
Austin Northwest C3/A322202/02/202012004601/08/202012004601/05/202010004501/21/2020120041
Audubon C38101/08/202011004702/22/202011004502/02/202013004501/05/2020120044
St. Edwards University C16051 N02/22/202012004202/02/202011004001/08/202011004001/05/2020100040
Houston-Galveston-Brazoria
Houston East C1/G316202/02/202011004802/22/202011004401/05/202011004402/08/2020110043
Houston Aldine C8/AF108/X150 202/02/202011004902/22/202011004602/08/202011004402/07/2020110043
Channelview C15/AH115 302/02/202011004602/08/202012004202/22/202011004101/05/2020100041
Northwest Harris Co. C26/A110/X154202/02/202012005002/22/202012004702/08/202012004602/07/2020110045
Hou.DeerPrk2 C35/235/1001/AFH139FP239102/08/202011004702/02/202010004702/22/202011004501/08/2020120043
Seabrook Friendship Park C45102/22/202012004502/02/202011004402/16/202011004302/08/2020110041
Houston Bayland Park C53/A146 102/22/202012005002/02/202011004802/16/202013004702/08/2020120046
Conroe Relocated C78/A321102/22/202012004801/08/202012004602/07/202011004501/05/2020110045
Manvel Croix Park C84102/22/202011004702/02/202011004702/16/202012004501/08/2020110044
Clinton C403/C304/AH113 302/08/202012004302/02/202011004101/26/202010003801/20/2020100038
Houston North Wayside C405102/22/202011004002/08/202011003802/02/202010003801/19/2020100035
Houston Monroe C406102/02/202011004302/22/202011004002/08/202011004001/08/2020120040
Lang C408202/02/202011004602/22/202012004402/08/202011004202/07/2020100042
Houston Croquet C409202/22/202012004602/02/202011004402/16/202013004302/08/2020110041
Houston Westhollow C410102/22/202012004702/02/202011004602/08/202012004501/08/2020110043
Park Place C416102/22/202012004202/08/202011004201/08/202012004001/05/2020100040
Sheldon C5511 N02/02/202011004702/22/202011004402/08/202011004202/07/2020100041
Baytown Wetlands Center C5521 N02/22/202012004802/08/202011004702/02/202010004602/16/2020110044
Crosby Library C5531 N01/08/202011004701/05/202011004602/02/202010004301/07/2020100043
West Houston C5541 N01/08/202011004001/05/202010003802/08/202012003702/22/2020170036
La Porte Sylvan Beach C5561 N02/16/202011005102/22/202013004702/02/202012004701/08/2020120043
Mercer Arboretum C5571 N02/22/202011004602/02/202011004502/07/202011004202/08/2020100041
Tom Bass C5581 N02/16/202013004602/02/202012004602/22/202011004502/08/2020110043
Katy Park C5591 N02/02/202011004702/22/202012004602/08/202012004501/08/2020110043
Atascocita C5601 N02/22/202012004502/02/202011004402/08/202012004201/08/2020120041
Meyer Park C5611 N02/02/202011005002/22/202013004702/07/202011004602/08/2020110045
Bunker Hill Village C5621 N02/22/202013004602/02/202011004502/08/202012004202/07/2020110040
Huffman Wolf Road C5631 N02/22/202012005102/02/202011004902/08/202011004501/08/2020110045
HRM-3 Haden Road C603/A114 1 N02/02/202011004502/22/202011004102/08/202010004001/05/2020100040
Wallisville Road C617 1 N02/22/202012004802/08/202011004802/02/202010004802/23/2020110045
Danciger C618 1 N01/08/202011004902/08/202012004802/07/202011004701/25/2020110046
Texas City 34th St. C620 1 N02/16/202011005702/02/202010005202/22/202013005002/07/2020100048
UH Moody Tower C6951 N02/02/202011004802/22/202012004602/08/202011004401/05/2020100043
UH WG Jones Forest C6981 N02/02/202012005002/07/202012004802/08/202011004402/01/2020120044
UH West Liberty C6991 N02/22/202011004502/02/202011004502/08/202011004201/08/2020120042
Lynchburg Ferry C1015/A165 102/08/202011004302/02/202012004302/22/202012004202/03/2020090040
Lake Jackson C1016 102/22/202011004902/16/202011004802/02/202011004802/07/2020100046
Baytown Garth C1017102/22/202012004602/08/202012004602/02/202011004501/08/2020110044
Galveston 99th St. C1034/A320/X183102/22/202012005002/16/202010004901/25/202020004902/02/2020110048
Oyster Creek C1607 1 N02/16/202012004902/22/202011004602/08/202012004402/02/2020100044
San Antonio
San Antonio Northwest C23202/22/202011004801/27/202012004802/02/202010004601/08/2020110046
Camp Bullis C58 102/22/202011004902/02/202010004801/27/202011004701/21/2020110044
Calaveras Lake C59102/22/202011005101/27/202011004901/08/202010004902/07/2020110046
Fair Oaks Ranch C5021 N02/22/202010004402/23/2020090032No DataNo Data
Bulverde Elementary C5031 N02/22/202011004202/23/2020100032No DataNo Data
New Braunfels Airport C5041 N02/22/202010004502/16/202010003502/23/202010003402/21/2020110030
City of Garden Ridge C5051 N02/22/202011004402/23/202010003402/21/2020100034No Data
Seguin Outdoor Learning Center C5061 N02/22/202011004602/23/202010003502/21/2020110032No Data
Heritage Middle School C6221 N01/27/202011004501/08/202011004402/02/202011004201/21/2020110042
CPS Pecan Valley C6781 N02/22/202011004502/23/202010003402/21/202011003302/17/2020110026
Government Canyon C16101 N02/23/2020100031No DataNo DataNo Data
Corpus Christi-Victoria
Corpus Christi West C4202/02/202012004701/08/202010004402/07/202013004102/01/2020110041
Corpus Christi Tuloso C21102/22/202010004402/02/202011004302/15/202010004101/08/2020100041
Victoria C87102/22/202010004702/02/202011004701/05/202010004701/08/2020100046
Lower Rio Grande Valley
Mission C43/AP143101/07/202012004301/20/202013004202/13/202012004102/22/2020110038
Harlingen Teege C1023101/07/202011004302/02/202011004001/20/202011004001/29/2020130039
Laredo
Laredo Vidaurri C44/AFGP144/P244102/02/202011004102/07/202010004001/27/202011004002/22/2020100039
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.