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Peak Daily One-Hour Ozone Averages for March 2021

The table below lists the peak daily one-hour ozone concentrations measured in March 2021 in each community where the TCEQ measures ozone. Concentrations are color-highlighted based on the EPA-defined Air Quality Index colors. (See Interpreting the AQI.) All ozone measurements are in parts per billion, and are truncated to an integer number.

The values that go into this table are calculated at 3:30 am each morning. Therefore, the current day will almost always have very low hourly averages that are not truly representative of local conditions for the day. Because of this, the report does not display the current day's data.

Use the selection boxes below to customize this report. You may select a different month, a different year, a different report format, and whether or not to include time on the report. Click on the Generate Report button once you have made your selections.

Month:Year:Report Format: Include time:
Include time
Highlight using AQI colors
AreaMonitoring SitePOCMarch 2021
Dallas-Fort Worth
Ft. Worth Northwest C13/AH302 244
Keller C17240
Frisco C31/C680141
Midlothian OFW C52/A137139
Denton Airport South C56/A163/X157142
Arlington Municipal Airport C61139
Dallas North No.2 C63/C679139
Rockwall Heath C69136
Grapevine Fairway C70/A301/X182141
Kaufman C71/A304/X071130
Granbury C73/C681143
Eagle Mountain Lake C75 145
Parker County C76144
Cleburne Airport C77/C682143
Dallas Hinton St. C401/C60/AH161 341
Dallas Executive Airport C402141
Greenville C1006/A198137
Pilot Point C1032143
Italy C1044/A323139
Corsicana Airport C1051132
AreaMonitoring SitePOCMarch 2021
Longview C19/A127/C644229
Tyler Airport Relocated C82131
Karnack C85/AFHP303133
AreaMonitoring SitePOCMarch 2021
El Paso-Juarez
El Paso UTEP C12/A125/X151/G125245
Ascarate Park SE C37/A332/A172/X159143
Chamizal C41/AH126 144
Socorro Hueco C49/F312146
Skyline Park C72147
Ivanhoe C414/F514145
AreaMonitoring SitePOCMarch 2021
Waco Mazanec C1037137
Temple Georgia C1045139
Killeen Skylark Field C1047140
AreaMonitoring SitePOCMarch 2021
Beaumont-Port Arthur
Beaumont-Downtown C2/A112/C2002 234
West Orange C9/A141234
Port Arthur West C28/A128/A228134
Hamshire C64/C654135
SETRPC 40 Sabine Pass C640/C1654130
SETRPC Mauriceville 42 C642/C311/C6651 N39
SETRPC 43 Jefferson Co Airport C643133
Nederland High School C1035 134
AreaMonitoring SitePOCMarch 2021
Austin North Hills Drive C3/A322237
Audubon C38136
Dripping Springs School C6141 N35
CAPCOG Lake Georgetown C6901 N34
Lockhart C16041 N36
CAPCOG Bastrop CAMS16121 N36
CAPCOG Elgin C16131 N32
CAPCOG East Austin C16191 N32
CAPCOG San Marcos Staples Road C16751 N37
AreaMonitoring SitePOCMarch 2021
Houston East C1/G316228
Houston Aldine C8/AF108/X150 233
Channelview C15/AH115 333
Northwest Harris Co. C26/A110/X154231
Hou.DeerPrk2 C35/235/1001/AFH139FP239131
Seabrook Friendship Park C45128
Conroe Relocated C78/A321135
Manvel Croix Park C84130
Clinton C403/C304/AH113 333
Houston North Wayside C405129
Houston Monroe C406128
Lang C408230
Houston Croquet C409225
Houston Westhollow C410/C3003122
Park Place C416128
Houston Harvard Street C417125
Sheldon C5511 N52
Baytown Wetlands Center C5521 N30
Crosby Library C5531 N31
West Houston C5541 N27
Mercer Arboretum C5571 N28
Tom Bass C5581 N29
Katy Park C5591 N30
Atascocita C5601 N30
Meyer Park C5611 N31
Bunker Hill Village C5621 N26
Huffman Wolf Road C5631 N36
Wallisville Road C617 1 N35
Texas City 34th St. C620 1 N36
UH Moody Tower C6951 N31
UH WG Jones Forest C6981 N37
Lynchburg Ferry C1015/A165 131
Lake Jackson C1016 128
Baytown Garth C1017136
Galveston 99th St. C1034/A320/X183134
Oyster Creek C1607 1 N33
AreaMonitoring SitePOCMarch 2021
San Antonio
San Antonio Northwest C23240
Calaveras Lake C59138
Elm Creek Elementary C5011 N36
Fair Oaks Ranch C5021 N38
Heritage Middle School C6221 N37
CPS Pecan Valley C6781 N31
Government Canyon C16101 N37
AreaMonitoring SitePOCMarch 2021
Corpus Christi-Victoria
Corpus Christi West C4231
Corpus Christi Tuloso C21131
Victoria C87133
AreaMonitoring SitePOCMarch 2021
Lower Rio Grande Valley
Mission C43/AP143130
Harlingen Teege C1023124
AreaMonitoring SitePOCMarch 2021
Laredo Vidaurri C44/AFGP144/P244135
 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.