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Eight-Hour Ozone High Value Days for 2020
as of May 29

The table below lists the daily maximum eight-hour ozone concentrations measured which meet or exceed 71 parts per billion in 2020 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.

Use the selection boxes below to customize this report. You may select a different year, a different sorting order, or a different report format. Click on the Generate Report button once you have made your selections.

YearSort ByReport Format
Highlight with AQI colors
2020 Sorted by Maximum Value
LocationRegionCAMSAQSDateTimeValuePOC
Texas City 34th St. C620 12 62048_167_0056May 18 202010:00881 N
Houston East C1/G316 12 148_201_1034May 18 202010:00862
Grapevine Fairway C70/A301/X182 4 7048_439_3009May 19 202010:00861
Baytown Wetlands Center C552 12 55248_201_0552May 18 202010:00851 N
Ft. Worth Northwest C13/AH302 4 1348_439_1002May 19 202011:00832
Camp Bullis C58 13 5848_029_0052April 30 202011:00811
Channelview C15/AH115 12 1548_201_0026May 18 202010:00813
Wallisville Road C617 12 61748_201_0617May 18 202011:00811 N
Baytown Garth C1017 12 101748_201_1017May 18 202011:00811
Hou.DeerPrk2 C35/235/1001/AFH139FP239 12 3548_201_1039May 18 202010:00811
La Porte Sylvan Beach C556 12 55648_201_0556May 18 202010:00791 N
HRM-3 Haden Road C603/A114 12 60348_201_0803May 18 202010:00791 N
Pilot Point C1032 4 103248_121_1032May 18 202012:00781
UH Moody Tower C695 12 69548_201_0695May 18 202010:00771 N
Galveston 99th St. C1034/A320/X183 12 103448_167_1034May 18 202010:00761
Lynchburg Ferry C1015/A165 12 101548_201_1015May 18 202010:00761
Dallas Hinton St. C401/C60/AH161 4 40148_113_0069May 19 202011:00753
Denton Airport South C56/A163/X157 4 5648_121_0034May 18 202011:00751
El Paso UTEP C12/A125/X151/G125 6 1248_141_0037May 9 202011:00752
Texas City 34th St. C620 12 62048_167_0056April 23 202010:00751 N
Seabrook Friendship Park C45 12 4548_201_1050May 18 202010:00751
UH Launch Trailer C1611 12 161148_201_1611May 18 202010:00751 N
Conroe Relocated C78/A321 12 7848_339_0078May 1 202010:00751
El Paso UTEP C12/A125/X151/G125 6 1248_141_0037May 6 202010:00742
Houston Aldine C8/AF108/X150 12 848_201_0024May 18 202011:00742
Northwest Harris Co. C26/A110/X154 12 2648_201_0029May 11 202011:00742
Eagle Mountain Lake C75 4 7548_439_0075May 19 202010:00741
Keller C17 4 1748_439_2003May 19 202011:00742
Frisco C31/C680 4 3148_085_0005May 18 202011:00731
Socorro Hueco C49/F312 6 4948_141_0057May 9 202011:00731
Camp Bullis C58 13 5848_029_0052April 20 202011:00721
Dallas North No.2 C63/C679 4 6348_113_0075May 19 202010:00721
Chamizal C41/AH126 6 4148_141_0044May 9 202011:00721
Houston Bayland Park C53/A146 12 5348_201_0055April 20 202012:00721
Dripping Springs School C614 11 61448_209_0614May 18 202011:00721 N
Conroe Relocated C78/A321 12 7848_339_0078April 24 202011:00721
Dallas North No.2 C63/C679 4 6348_113_0075May 18 202012:00711
Houston Westhollow C410 12 41048_201_0066April 20 202012:00711
Huffman Wolf Road C563 12 56348_201_0563May 18 202012:00711 N
Clinton C403/C304/AH113 12 40348_201_1035May 18 202010:00713
UH WG Jones Forest C698 12 69848_339_0698May 1 202010:00711 N
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.