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One-Hour Ozone High Value Days for 2015
as of September 4

In July 1997, the U. S. Environmental Protection Agency (EPA) announced a new National Ambient Air Quality Standard for ground-level ozone. The EPA is phasing out and replacing the previous one-hour standard with a new eight-hour standard to protect public health against longer exposure to the air pollutant.

A community will meet the new standard when the three-year average of the fourth-highest daily maximum eight-hour concentration measured at each monitoring site is less than 85 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. All times shown are in 24-hour format and are Local Standard Time. These times correspond to the beginning of the hourly average.

YearSort ByReport Format
Highlight with AQI colors
The table below lists the one-hour ozone concentrations measured in 2015 in each community where TCEQ measures ozone that are equal to or higher than 125 parts per billion. All ozone measurements are in parts per billion. Concentrations are color-highlighted based on the EPA-defined Air Quality Index colors. (See Interpreting the AQI.)

2015 -- Sorted by Maximum Value
LocationRegionCAMSAQSDateTimeValuePOCHours
Exceeded
UH Moody Tower C6951269548_201_0695August 10 201515:001411 N2
La Porte Sylvan Beach C5561255648_201_0556August 10 201514:001381 N1
Houston Aldine C8/AF108/X150 12848_201_0024August 29 201514:0013622
Houston Aldine C8/AF108/X150 12848_201_0024June 3 201515:0013522
Park Place C4161241648_201_0416August 10 201515:0013511
HRM-3 Haden Road C603/A114 1260348_201_0803June 3 201514:001331 N2
Park Place C4161241648_201_0416August 13 201515:0013211
Lang C4081240848_201_0047August 3 201515:0013121
Park Place C4161241648_201_0416August 12 201516:0013112
UH Moody Tower C6951269548_201_0695August 13 201515:001311 N2
Houston East C1/G31612148_201_1034June 3 201514:0013022
Houston Bayland Park C53/A146 125348_201_0055August 28 201517:0012811
HRM-3 Haden Road C603/A114 1260348_201_0803August 13 201513:001281 N1
Galveston 99th St. C1034/A320/X18312103448_167_1034August 12 201516:0012611
UH Moody Tower C6951269548_201_0695August 12 201516:001261 N1
HRM-3 Haden Road C603/A114 1260348_201_0803August 3 201512:001261 N1
Houston Aldine C8/AF108/X150 12848_201_0024August 13 201514:0012522
Houston Texas Avenue C4111241148_201_0075August 10 201516:0012511
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.

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.

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.