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Eight-Hour Ozone High Value Days for 2019
as of April 24

The table below lists the daily maximum eight-hour ozone concentrations measured which meet or exceed 71 parts per billion in 2019 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
2019 Sorted by Maximum Value
Tyler Airport Relocated C82 5 8248_423_0007April 9 201911:00801
Galveston 99th St. C1034/A320/X183 12 103448_167_1034March 22 201913:00791
Conroe Relocated C78/A321 12 7848_339_0078March 22 201911:00781
UH Moody Tower C695 12 69548_201_0695March 20 201911:00771 N
Clinton C403/C304/AH113 12 40348_201_1035March 20 201910:00773
UH WG Jones Forest C698 12 69848_339_0698March 22 201911:00771 N
Hou.DeerPrk2 C35/235/1001/AFH139FP239 12 3548_201_1039April 9 201912:00761
UH Moody Tower C695 12 69548_201_0695April 9 201911:00751 N
Conroe Relocated C78/A321 12 7848_339_0078April 21 201910:00751
Longview C19/A127/C644 5 1948_183_0001April 9 201911:00742
Houston Aldine C8/AF108/X150 12 848_201_0024April 9 201911:00742
Wallisville Road C617 12 61748_201_0617April 9 201911:00741 N
SETRPC 43 Jefferson Co Airport C643 10 64348_245_0102March 22 201911:00741
Oyster Creek C1607 12 160748_039_1607March 22 201910:00731 N
Houston Aldine C8/AF108/X150 12 848_201_0024March 27 201910:00732
Channelview C15/AH115 12 1548_201_0026April 9 201911:00733
Baytown Garth C1017 12 101748_201_1017April 9 201911:00731
Hou.DeerPrk2 C35/235/1001/AFH139FP239 12 3548_201_1039March 20 201912:00731
Killeen Skylark Field C1047 9 104748_027_1047April 9 201911:00721
Texas City 34th St. C620 12 62048_167_0056April 9 201910:00721 N
Northwest Harris Co. C26/A110/X154 12 2648_201_0029March 22 201910:00722
Park Place C416 12 41648_201_0416April 9 201911:00721
HRM-3 Haden Road C603/A114 12 60348_201_0803March 20 201910:00721 N
Conroe Relocated C78/A321 12 7848_339_0078April 15 201911:00721
Manvel Croix Park C84 12 8448_039_1004March 20 201911:00711
Texas City 34th St. C620 12 62048_167_0056March 21 201911:00711 N
Houston Aldine C8/AF108/X150 12 848_201_0024March 20 201911:00712
Houston Aldine C8/AF108/X150 12 848_201_0024March 22 201910:00712
HRM-3 Haden Road C603/A114 12 60348_201_0803April 9 201911:00711 N
UH WG Jones Forest C698 12 69848_339_0698April 9 201911:00711 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.