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Eight-Hour Ozone High Value Days for 2017
as of October 23

The table below lists the daily maximum eight-hour ozone concentrations measured which meet or exceed 71 parts per billion in 2017 in each community where the TCEQ measures ozone. This information is updated hourly. Concentrations are color-highlighted based on the EPA-defined Air Quality Index colors. (See Interpreting the AQI.) Times shown are in 24-hour format and are Local Standard Time. Our convention is that the time reflects the beginning of the eight-hour average. All ozone measurements are in parts per billion.

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YearSort ByReport Format
Highlight with AQI colors
2017 Sorted by Maximum Value
LocationRegionCAMSAQSDateTimeValuePOC
Houston Bayland Park C53/A146 12 5348_201_0055September 1 201711:00951
Camp Bullis C58 13 5848_029_0052June 8 201711:00891
Seabrook Friendship Park C45 12 4548_201_1050September 12 201711:00891
Manvel Croix Park C84 12 8448_039_1004June 8 201710:00871
Bulverde Elementary C503 13 50348_091_0503June 8 201711:00871 N
Texas City 34th St. C620 12 62048_167_0056September 12 201711:00871 N
UH WG Jones Forest C698 12 69848_339_0698September 14 201710:00851 N
Crosby Library C553 12 55348_201_0553May 6 201711:00841 N
Baytown Garth C1017 12 101748_201_1017May 6 201710:00841
Cleburne Airport C77/C682 4 7748_251_0003June 7 201710:00841
UH Coastal Center C697 12 69748_167_0697September 12 201711:00831 N
Galveston 99th St. C1034/A320/X183 12 103448_167_1034September 12 201711:00831
Crosby Library C553 12 55348_201_0553April 24 201710:00831 N
UH WG Jones Forest C698 12 69848_339_0698May 7 201710:00831 N
Grapevine Fairway C70/A301/X182 4 7048_439_3009August 4 201710:00831
Dallas Hinton St. C401/C60/AH161 4 40148_113_0069September 1 201712:00823
Chamizal C41/AH126 6 4148_141_0044September 12 201710:00821
U of H-Sugarland C696 12 69648_157_0696June 8 201711:00821 N
U of H-Sugarland C696 12 69648_157_0696September 8 201711:00821 N
Clear Creek High School C571 12 57148_167_0571September 12 201711:00821 N
Wallisville Road C617 12 61748_201_0617May 6 201710:00821 N
Conroe Relocated C78/A321 12 7848_339_0078September 14 201711:00821
City of Garden Ridge C505 13 50548_091_0505June 8 201711:00811 N
Dallas North No.2 C63/C679 4 6348_113_0075September 1 201712:00811
Dallas North No.2 C63/C679 4 6348_113_0075September 13 201711:00811
UH Moody Tower C695 12 69548_201_0695May 6 201711:00811 N
HRM-3 Haden Road C603/A114 12 60348_201_0803May 6 201710:00811 N
Houston East C1/G316 12 148_201_1034May 6 201710:00812
Hou.DeerPrk2 C35/235/1001/AFH139FP239 12 3548_201_1039May 6 201710:00811
Granbury C73/C681 4 7348_221_0001July 31 201713:00811
Cleburne Airport C77/C682 4 7748_251_0003July 31 201712:00811
Conroe Relocated C78/A321 12 7848_339_0078April 7 201711:00811
Keller C17 4 1748_439_2003September 13 201711:00812
Temple Georgia C1045 9 104548_027_1045September 13 201710:00801
San Antonio Northwest C23 13 2348_029_0032June 8 201711:00802
Manvel Croix Park C84 12 8448_039_1004May 6 201711:00801
Dallas Hinton St. C401/C60/AH161 4 40148_113_0069May 6 201711:00803
Dallas North No.2 C63/C679 4 6348_113_0075May 6 201711:00801
Denton Airport South C56/A163/X157 4 5648_121_0034June 8 201711:00801
Skyline Park C72 6 7248_141_0058June 7 201712:00801
Houston Aldine C8/AF108/X150 12 848_201_0024October 18 201710:00802
Northwest Harris Co. C26/A110/X154 12 2648_201_0029October 13 201711:00802
UH Moody Tower C695 12 69548_201_0695September 1 201709:00801 N
Nederland High School C1035 10 103548_245_1035September 13 201710:00801
Conroe Relocated C78/A321 12 7848_339_0078April 24 201712:00801
UH WG Jones Forest C698 12 69848_339_0698April 24 201711:00801 N
Skyline Park C72 6 7248_141_0058September 12 201710:00791
La Porte Sylvan Beach C556 12 55648_201_0556September 12 201712:00791 N
Port Arthur West C28/A128/A228 10 2848_245_0011September 13 201709:00791
Conroe Relocated C78/A321 12 7848_339_0078May 15 201710:00791
UH WG Jones Forest C698 12 69848_339_0698April 7 201712:00791 N
Ft. Worth Northwest C13/AH302 4 1348_439_1002May 30 201710:00792
Keller C17 4 1748_439_2003August 4 201711:00792
Arlington Municipal Airport C61 4 6148_439_3011September 1 201711:00791
Manvel Croix Park C84 12 8448_039_1004September 30 201710:00781
Dallas Hinton St. C401/C60/AH161 4 40148_113_0069August 4 201711:00783
Ascarate Park SE C37/A332/A172/X159 6 3748_141_0055September 12 201710:00781
Channelview C15/AH115 12 1548_201_0026May 6 201712:00783
Northwest Harris Co. C26/A110/X154 12 2648_201_0029October 18 201711:00782
UH Moody Tower C695 12 69548_201_0695October 12 201710:00781 N
Baytown Garth C1017 12 101748_201_1017April 7 201711:00781
Clinton C403/C304/AH113 12 40348_201_1035May 6 201711:00783
Clinton C403/C304/AH113 12 40348_201_1035September 1 201709:00783
Clinton C403/C304/AH113 12 40348_201_1035September 3 201710:00783
Seabrook Friendship Park C45 12 4548_201_1050August 4 201710:00781
Hamshire C64/C654 10 6448_245_0022September 13 201710:00781
UH West Liberty C699 12 69948_291_0699April 7 201711:00781 N
Grapevine Fairway C70/A301/X182 4 7048_439_3009June 8 201711:00781
Arlington Municipal Airport C61 4 6148_439_3011September 13 201711:00781
Elm Creek Elementary C501 13 50148_029_0501May 13 201712:00771 N
Heritage Middle School C622 13 62248_029_0622June 8 201711:00771 N
Manvel Croix Park C84 12 8448_039_1004May 23 201711:00771
Manvel Croix Park C84 12 8448_039_1004October 18 201710:00771
Frisco C31/C680 4 3148_085_0005September 2 201710:00771
Dallas North No.2 C63/C679 4 6348_113_0075August 4 201710:00771
Midlothian OFW C52/A137 4 5248_139_0016June 7 201710:00771
Lang C408 12 40848_201_0047October 12 201711:00772
Houston Bayland Park C53/A146 12 5348_201_0055October 18 201710:00771
Houston Westhollow C410 12 41048_201_0066October 18 201711:00771
Park Place C416 12 41648_201_0416September 1 201709:00771
Clear Brook High School C570 12 57048_201_0570September 12 201711:00771 N
Clinton C403/C304/AH113 12 40348_201_1035September 2 201711:00773
Conroe Relocated C78/A321 12 7848_339_0078May 7 201710:00771
UH WG Jones Forest C698 12 69848_339_0698May 15 201711:00771 N
Ft. Worth Northwest C13/AH302 4 1348_439_1002August 4 201711:00772
Pilot Point C1032 4 103248_121_1032June 8 201711:00761
U of H-Sugarland C696 12 69648_157_0696October 18 201711:00761 N
Texas City 34th St. C620 12 62048_167_0056August 4 201710:00761 N
Galveston 99th St. C1034/A320/X183 12 103448_167_1034May 12 201711:00761
Houston Aldine C8/AF108/X150 12 848_201_0024May 6 201711:00762
Houston Aldine C8/AF108/X150 12 848_201_0024May 14 201710:00762
Northwest Harris Co. C26/A110/X154 12 2648_201_0029June 9 201711:00762
Houston North Wayside C405 12 40548_201_0046May 6 201711:00761
Atascocita C560 12 56048_201_0560September 14 201710:00761 N
Hou.DeerPrk2 C35/235/1001/AFH139FP239 12 3548_201_1039September 12 201712:00761
Cleburne Airport C77/C682 4 7748_251_0003August 3 201711:00761
UH WG Jones Forest C698 12 69848_339_0698May 2 201710:00761 N
UH WG Jones Forest C698 12 69848_339_0698June 9 201710:00761 N
Eagle Mountain Lake C75 4 7548_439_0075August 4 201711:00761
Temple Georgia C1045 9 104548_027_1045May 6 201710:00751
San Antonio Northwest C23 13 2348_029_0032August 1 201710:00752
Camp Bullis C58 13 5848_029_0052September 13 201711:00751
Fair Oaks Ranch C502 13 50248_029_0502June 8 201711:00751 N
Dallas Hinton St. C401/C60/AH161 4 40148_113_0069September 13 201712:00753
Ivanhoe C414 6 41448_141_0029June 27 201712:00751
El Paso UTEP C12/A125/X151 6 1248_141_0037June 6 201710:00752
El Paso UTEP C12/A125/X151 6 1248_141_0037June 27 201710:00752
Skyline Park C72 6 7248_141_0058June 27 201711:00751
Skyline Park C72 6 7248_141_0058September 7 201709:00751
Lang C408 12 40848_201_0047October 1 201710:00752
Houston Bayland Park C53/A146 12 5348_201_0055October 12 201711:00751
Wallisville Road C617 12 61748_201_0617April 7 201710:00751 N
Baytown Garth C1017 12 101748_201_1017April 24 201710:00751
Cleburne Airport C77/C682 4 7748_251_0003July 29 201715:00751
UH West Liberty C699 12 69948_291_0699April 24 201711:00751 N
Eagle Mountain Lake C75 4 7548_439_0075May 30 201711:00751
Keller C17 4 1748_439_2003May 6 201712:00752
Keller C17 4 1748_439_2003June 23 201712:00752
Arlington Municipal Airport C61 4 6148_439_3011August 3 201711:00751
CAPCOG Lake Georgetown C690 11 69048_491_0690June 8 201711:00751 N
San Antonio Northwest C23 13 2348_029_0032May 7 201710:00742
Lockhart C1604 11 160448_055_1604June 7 201710:00741 N
Lockhart C1604 11 160448_055_1604September 12 201709:00741 N
Bulverde Elementary C503 13 50348_091_0503September 13 201710:00741 N
El Paso UTEP C12/A125/X151 6 1248_141_0037July 28 201711:00742
El Paso UTEP C12/A125/X151 6 1248_141_0037August 17 201711:00742
Chamizal C41/AH126 6 4148_141_0044June 4 201710:00741
Chamizal C41/AH126 6 4148_141_0044June 27 201710:00741
U of H-Sugarland C696 12 69648_157_0696May 6 201711:00741 N
Galveston 99th St. C1034/A320/X183 12 103448_167_1034May 6 201713:00741
Houston Aldine C8/AF108/X150 12 848_201_0024October 1 201710:00742
Northwest Harris Co. C26/A110/X154 12 2648_201_0029May 14 201711:00742
Northwest Harris Co. C26/A110/X154 12 2648_201_0029September 4 201711:00742
Houston Croquet C409 12 40948_201_0051May 6 201711:00742
Houston Croquet C409 12 40948_201_0051June 8 201710:00742
Houston Bayland Park C53/A146 12 5348_201_0055May 6 201711:00741
Houston Westhollow C410 12 41048_201_0066October 12 201711:00741
Clear Brook High School C570 12 57048_201_0570May 6 201711:00741 N
Wallisville Road C617 12 61748_201_0617April 24 201710:00741 N
UH Moody Tower C695 12 69548_201_0695September 2 201711:00741 N
Clinton C403/C304/AH113 12 40348_201_1035October 12 201710:00743
Hou.DeerPrk2 C35/235/1001/AFH139FP239 12 3548_201_1039September 2 201709:00741
Beaumont-Downtown C2/A112/C2002 10 248_245_0009September 13 201710:00742
Cleburne Airport C77/C682 4 7748_251_0003September 13 201710:00741
Kaufman C71/A304/X071 4 7148_257_0005September 13 201711:00741
Waco Mazanec C1037 9 103748_309_1037May 6 201710:00741
Parker County C76 4 7648_367_0081May 30 201711:00741
Ft. Worth Northwest C13/AH302 4 1348_439_1002May 13 201712:00742
Keller C17 4 1748_439_2003September 1 201712:00742
San Antonio Northwest C23 13 2348_029_0032August 4 201711:00732
Frisco C31/C680 4 3148_085_0005May 6 201712:00731
Frisco C31/C680 4 3148_085_0005August 10 201712:00731
Dallas North No.2 C63/C679 4 6348_113_0075August 10 201711:00731
Denton Airport South C56/A163/X157 4 5648_121_0034May 7 201710:00731
Denton Airport South C56/A163/X157 4 5648_121_0034May 31 201710:00731
Denton Airport South C56/A163/X157 4 5648_121_0034October 19 201710:00731
Pilot Point C1032 4 103248_121_1032September 14 201711:00731
El Paso UTEP C12/A125/X151 6 1248_141_0037June 4 201710:00732
Texas City 34th St. C620 12 62048_167_0056May 6 201711:00731 N
Galveston 99th St. C1034/A320/X183 12 103448_167_1034May 7 201703:00731
Galveston 99th St. C1034/A320/X183 12 103448_167_1034June 8 201711:00731
Houston Aldine C8/AF108/X150 12 848_201_0024September 14 201709:00732
Northwest Harris Co. C26/A110/X154 12 2648_201_0029October 1 201711:00732
Houston Bayland Park C53/A146 12 5348_201_0055June 8 201710:00731
Park Place C416 12 41648_201_0416May 6 201710:00731
Crosby Library C553 12 55348_201_0553September 13 201710:00731 N
Atascocita C560 12 56048_201_0560October 18 201710:00731 N
Baytown Garth C1017 12 101748_201_1017September 13 201710:00731
Houston East C1/G316 12 148_201_1034October 1 201710:00732
Houston East C1/G316 12 148_201_1034October 12 201710:00732
Clinton C403/C304/AH113 12 40348_201_1035October 1 201710:00733
Seabrook Friendship Park C45 12 4548_201_1050May 6 201711:00731
Beaumont-Downtown C2/A112/C2002 10 248_245_0009May 14 201710:00732
Cleburne Airport C77/C682 4 7748_251_0003May 13 201711:00731
Cleburne Airport C77/C682 4 7748_251_0003September 11 201710:00731
Conroe Relocated C78/A321 12 7848_339_0078May 2 201710:00731
Conroe Relocated C78/A321 12 7848_339_0078June 9 201710:00731
Corsicana Airport C1051 4 105148_349_1051September 12 201710:00731
Ft. Worth Northwest C13/AH302 4 1348_439_1002September 13 201711:00732
Grapevine Fairway C70/A301/X182 4 7048_439_3009June 23 201712:00731
Grapevine Fairway C70/A301/X182 4 7048_439_3009September 13 201711:00731
Audubon C38 11 3848_453_0020June 8 201710:00731
CAPCOG Lake Georgetown C690 11 69048_491_0690May 6 201711:00731 N
CAPCOG Lake Georgetown C690 11 69048_491_0690September 13 201710:00731 N
Temple Georgia C1045 9 104548_027_1045May 7 201711:00721
Temple Georgia C1045 9 104548_027_1045June 7 201712:00721
Camp Bullis C58 13 5848_029_0052May 7 201711:00721
Camp Bullis C58 13 5848_029_0052August 1 201710:00721
Camp Bullis C58 13 5848_029_0052August 4 201711:00721
Fair Oaks Ranch C502 13 50248_029_0502September 13 201711:00721 N
Manvel Croix Park C84 12 8448_039_1004September 1 201710:00721
Manvel Croix Park C84 12 8448_039_1004September 12 201710:00721
Frisco C31/C680 4 3148_085_0005June 8 201710:00721
Frisco C31/C680 4 3148_085_0005September 18 201711:00721
Dallas North No.2 C63/C679 4 6348_113_0075June 8 201711:00721
Denton Airport South C56/A163/X157 4 5648_121_0034July 24 201712:00721
Denton Airport South C56/A163/X157 4 5648_121_0034September 14 201710:00721
Denton Airport South C56/A163/X157 4 5648_121_0034September 18 201712:00721
El Paso UTEP C12/A125/X151 6 1248_141_0037June 7 201710:00722
El Paso UTEP C12/A125/X151 6 1248_141_0037September 12 201710:00722
Chamizal C41/AH126 6 4148_141_0044May 20 201712:00721
Chamizal C41/AH126 6 4148_141_0044August 24 201711:00721
U of H-Sugarland C696 12 69648_157_0696September 30 201710:00721 N
Galveston 99th St. C1034/A320/X183 12 103448_167_1034April 7 201710:00721
Houston Westhollow C410 12 41048_201_0066June 8 201710:00721
Park Place C416 12 41648_201_0416September 2 201710:00721
Park Place C416 12 41648_201_0416October 12 201710:00721
Atascocita C560 12 56048_201_0560September 13 201711:00721 N
UH Moody Tower C695 12 69548_201_0695October 18 201710:00721 N
HRM-3 Haden Road C603/A114 12 60348_201_0803September 2 201710:00721 N
Dripping Springs School C614 11 61448_209_0614August 1 201711:00721 N
Granbury C73/C681 4 7348_221_0001September 30 201711:00721
SETRPC 40 Sabine Pass C640/C1654 10 64048_245_0101September 2 201708:00721
West Orange C9/A141 10 948_361_1001September 13 201709:00722
Rockwall Heath C69 4 6948_397_0001May 6 201711:00721
Ft. Worth Northwest C13/AH302 4 1348_439_1002May 6 201711:00722
Ft. Worth Northwest C13/AH302 4 1348_439_1002September 1 201711:00722
Keller C17 4 1748_439_2003May 30 201711:00722
Keller C17 4 1748_439_2003June 8 201711:00722
Grapevine Fairway C70/A301/X182 4 7048_439_3009October 19 201710:00721
Killeen Skylark Field C1047 9 104748_027_1047April 7 201711:00711
Danciger C618 12 61848_039_0618July 31 201711:00711 N
Frisco C31/C680 4 3148_085_0005June 23 201711:00711
Frisco C31/C680 4 3148_085_0005August 4 201710:00711
Dallas North No.2 C63/C679 4 6348_113_0075September 2 201710:00711
Denton Airport South C56/A163/X157 4 5648_121_0034May 6 201710:00711
Denton Airport South C56/A163/X157 4 5648_121_0034August 4 201711:00711
Italy C1044/A323 4 104448_139_1044September 12 201710:00711
El Paso UTEP C12/A125/X151 6 1248_141_0037June 5 201710:00712
El Paso UTEP C12/A125/X151 6 1248_141_0037July 10 201710:00712
El Paso UTEP C12/A125/X151 6 1248_141_0037August 24 201711:00712
Chamizal C41/AH126 6 4148_141_0044July 10 201709:00711
Houston Aldine C8/AF108/X150 12 848_201_0024May 7 201709:00712
Houston Aldine C8/AF108/X150 12 848_201_0024September 13 201710:00712
Houston Aldine C8/AF108/X150 12 848_201_0024October 13 201710:00712
Northwest Harris Co. C26/A110/X154 12 2648_201_0029May 7 201711:00712
Houston North Wayside C405 12 40548_201_0046May 14 201710:00711
Lang C408 12 40848_201_0047September 1 201709:00712
Houston Westhollow C410 12 41048_201_0066May 6 201711:00711
Clear Brook High School C570 12 57048_201_0570September 5 201710:00711 N
UH Moody Tower C695 12 69548_201_0695June 8 201710:00711 N
UH Moody Tower C695 12 69548_201_0695September 3 201710:00711 N
HRM-3 Haden Road C603/A114 12 60348_201_0803April 7 201710:00711 N
Granbury C73/C681 4 7348_221_0001June 21 201710:00711
Cleburne Airport C77/C682 4 7748_251_0003September 12 201710:00711
UH West Liberty C699 12 69948_291_0699September 13 201710:00711 N
Waco Mazanec C1037 9 103748_309_1037September 13 201710:00711
Eagle Mountain Lake C75 4 7548_439_0075June 8 201711:00711
Grapevine Fairway C70/A301/X182 4 7048_439_3009August 10 201711:00711
Grapevine Fairway C70/A301/X182 4 7048_439_3009September 18 201710:00711
Arlington Municipal Airport C61 4 6148_439_3011May 13 201711:00711
Arlington Municipal Airport C61 4 6148_439_3011June 7 201710:00711
Austin Northwest C3/A322 11 348_453_0014May 6 201710:00712
Austin Northwest C3/A322 11 348_453_0014June 8 201711:00712
Austin Northwest C3/A322 11 348_453_0014September 1 201710:00712
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.