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Eight-Hour Ozone High Value Days for 2015
as of May 27

The table below lists the daily maximum eight-hour ozone concentrations measured which meet or exceed 76 parts per billion in 2015 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
2015 Sorted by Maximum Value
LocationRegionCAMSAQSDateTimeValuePOC
Houston Aldine C8/AF108/X150 12 848_201_0024April 30 201511:00842
Channelview C15/AH115 12 1548_201_0026April 30 201510:00823
Baytown Garth C1017 12 101748_201_1017April 30 201510:00821
Rockwall Heath C69 4 6948_397_0001April 30 201511:00821
UH Moody Tower C695 12 69548_201_0695May 1 201511:00811 N
HRM-3 Haden Road C603/A114 12 60348_201_0803April 30 201510:00811 N
UH WG Jones Forest C698 12 69848_339_0698May 2 201511:00811 N
Galveston 99th St. C1034/A320/X183 12 103448_167_1034May 1 201511:00801
Conroe Relocated C78/A321 12 7848_339_0078May 2 201511:00801
Manvel Croix Park C84 12 8448_039_1004May 1 201510:00791
Dallas North No.2 C63/C679 4 6348_113_0075April 30 201511:00791
Houston Aldine C8/AF108/X150 12 848_201_0024May 1 201510:00792
Houston Bayland Park C53/A146 12 5348_201_0055May 1 201511:00791
Lynchburg Ferry C1015/A165 12 101548_201_1015April 30 201510:00791
Parker County C76 4 7648_367_0081May 1 201510:00791
Camp Bullis C58 13 5848_029_0052May 1 201511:00781
Pilot Point C1032 4 103248_121_1032May 2 201510:00781
Houston Aldine C8/AF108/X150 12 848_201_0024May 2 201510:00782
Houston Croquet C409 12 40948_201_0051May 1 201511:00782
HRM-3 Haden Road C603/A114 12 60348_201_0803May 1 201511:00781 N
Houston East C1/G316 12 148_201_1034April 30 201510:00782
Houston East C1/G316 12 148_201_1034May 1 201511:00782
San Antonio Northwest C23 13 2348_029_0032May 2 201510:00772
Frisco C31/C680 4 3148_085_0005May 2 201510:00771
Denton Airport South C56/A163/X157 4 5648_121_0034May 1 201511:00771
Texas City 34th St. C620 12 62048_167_0056May 1 201510:00771 N
Park Place C416 12 41648_201_0416May 1 201511:00771
Hou.DeerPrk2 C35/235/1001/AFH139FP239 12 3548_201_1039May 1 201511:00771
Eagle Mountain Lake C75 4 7548_439_0075May 1 201510:00771
Fair Oaks Ranch C502 13 50248_029_0502May 1 201511:00761 N
City of Garden Ridge C505 13 50548_091_0505April 30 201511:00761 N
Lang C408 12 40848_201_0047May 1 201511:00762
UH Moody Tower C695 12 69548_201_0695April 30 201511:00761 N
Keller C17 4 1748_439_2003May 1 201511:00762
Grapevine Fairway C70/A301/X182 4 7048_439_3009May 1 201511:00761
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 - 0.059
51 - 100 Not Defined 0.06 - 0.075
101 - 150 0.125 - 0.164 0.076 - 0.095
151 - 200 0.165 - 0.204 0.096 - 0.115
201 - 300 0.205 - 0.404 0.116 - 0.374
301 - 400 0.405 - 0.504 Not Defined
401 - 500 0.505 - 0.604 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.