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Eight-Hour Ozone High Value Days for 2016
as of April 29

The table below lists the daily maximum eight-hour ozone concentrations measured which meet or exceed 71 parts per billion in 2016 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
2016 Sorted by Maximum Value
LocationRegionCAMSAQSDateTimeValuePOC
Galveston 99th St. C1034/A320/X183 12 103448_167_1034April 23 201610:00841
Houston Bayland Park C53/A146 12 5348_201_0055April 15 201611:00831
Lang C408 12 40848_201_0047April 23 201611:00802
Houston Westhollow C410 12 41048_201_0066April 15 201611:00791
Houston Westhollow C410 12 41048_201_0066April 23 201610:00791
Northwest Harris Co. C26/A110/X154 12 2648_201_0029April 23 201611:00782
Houston Bayland Park C53/A146 12 5348_201_0055April 23 201610:00781
UH WG Jones Forest C698 12 69848_339_0698April 27 201612:00771 N
Houston Aldine C8/AF108/X150 12 848_201_0024April 27 201611:00752
Conroe Relocated C78/A321 12 7848_339_0078April 5 201611:00751
Conroe Relocated C78/A321 12 7848_339_0078April 27 201611:00751
Galveston 99th St. C1034/A320/X183 12 103448_167_1034April 7 201611:00741
Houston Aldine C8/AF108/X150 12 848_201_0024April 23 201611:00742
SETRPC 40 Sabine Pass C640/C1654 10 64048_245_0101April 4 201611:00741
UH WG Jones Forest C698 12 69848_339_0698March 26 201612:00741 N
UH WG Jones Forest C698 12 69848_339_0698April 5 201611:00741 N
Houston Aldine C8/AF108/X150 12 848_201_0024April 3 201611:00732
SETRPC 40 Sabine Pass C640/C1654 10 64048_245_0101April 7 201612:00731
Sheldon C551 12 55148_201_0551April 3 201610:00721 N
Galveston 99th St. C1034/A320/X183 12 103448_167_1034April 14 201611:00711
Crosby Library C553 12 55348_201_0553April 3 201613:00711 N
Bunker Hill Village C562 12 56248_201_0562April 23 201611:00711 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

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 beginning 1/1/2013, 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.