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Daily Maximum Eight-Hour Ozone Averages for April 2021

The table below lists the peak daily maximum eight-hour ozone concentrations measured in April 2021 in each community where the TCEQ measures ozone. Concentrations that are rated Moderate or higher are color-highlighted based on the EPA-defined Air Quality Index colors. (See Interpreting the AQI.) All ozone measurements are in parts per billion.

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 with AQI colors
AreaMonitoring SitePOCApril 2021
Dallas-Fort Worth
Ft. Worth Northwest C13/AH302 254514845443949564546595929
Keller C17255504744433645534442565828
Frisco C31/C680157515350473948594248596632
Midlothian OFW C52/A137158534947423148524048574530
Denton Airport South C56/A163/X157154545447503947614846626530
Arlington Municipal Airport C61156525048453748554446585330
Dallas North No.2 C63/C679154505048443748564146555629
Rockwall Heath C69151484742403343523343495227
Grapevine Fairway C70/A301/X182153464643403445513842525829
Kaufman C71/A304/X071154495043403445533345485330
Granbury C73/C681158574742434047484743575025
Eagle Mountain Lake C75 158585346474250584946626431
Parker County C76159594942444149535245595628
Cleburne Airport C77/C682159564846453949544946615133
Dallas Hinton St. C401/C60/AH161 356464847433648534046545129
Dallas Executive Airport C402158525249443749554147575330
Greenville C1006/A198152504945443645543447515627
Pilot Point C1032155525650504048604349636136
Italy C1044/A323155514848423547514048544731
Corsicana Airport C1051151484648443647523851535430
AreaMonitoring SitePOCApril 2021
Longview C19/A127/C644249494848433732522544495122
Tyler Airport Relocated C8215249484947NV52583249515430
Karnack C85/AFHP30314848485245362655264257NV8
AreaMonitoring SitePOCApril 2021
El Paso-Juarez
El Paso UTEP C12/A125/X151/G125248575461505153475355504335
Ascarate Park SE C37/A332/A172/X159145495051444950424952473734
Chamizal C41/AH126 140535157495052465253503829
Socorro Hueco C49/F312149535255514855505657534838
Skyline Park C72147524956525353485354534536
Ivanhoe C414/F514147525253525554495456514635
Ojo De Agua C1021/FG121/FG22115460616442545752NANANANANA
AreaMonitoring SitePOCApril 2021
Waco Mazanec C1037155574847443749494352594230
Temple Georgia C1045158634948473949555152624331
Killeen Skylark Field C10471NANV4944494251575251705031
AreaMonitoring SitePOCApril 2021
Beaumont-Port Arthur
Beaumont-Downtown C2/A112/C2002 249524953473332502347525637
West Orange C9/A141248504750463333532044505331
Port Arthur West C28/A128/A228147514951503435502347545637
Hamshire C64/C654152535051473334472443595534
SETRPC 40 Sabine Pass C640/C1654149524949513434482344495338
SETRPC Mauriceville 42 C642/C311/C6651 N53545157513839582850505333
SETRPC 43 Jefferson Co Airport C643153535050473233492347545334
Nederland High School C1035 150514951483434502348545333
AreaMonitoring SitePOCApril 2021
Austin North Hills Drive C3/A322253574246433845534954654627
Audubon C38154584043443746534852654520
Dripping Springs School C6141 N5661354042354455505671429
CAPCOG Lake Georgetown C6901 N50554241423541514647614518
Lockhart C16041 N53564045403443483958633827
St. Edwards University C16051 N49533942393341454152603823
CAPCOG Bastrop CAMS16121 N44483939342934403247523325
CAPCOG Elgin C16131 N48523538342840383250533421
CAPCOG East Austin C16191 N49543942413541474251603923
CAPCOG Round Rock Brushy Creek W C16201 N49533941393338484248593921
CAPCOG San Marcos Staples Road C16751 N49553942393340454153603825
AreaMonitoring SitePOCApril 2021
Houston East C1/G3162NANANANANVNV36532748765627
Houston Aldine C8/AF108/X150 254565058493738482954866333
Channelview C15/AH115 348514848463232452351625029
Northwest Harris Co. C26/A110/X154249554353433134522947706126
Hou.DeerPrk2 C35/235/1001/AFH139FP239151535249493535492853615532
Seabrook Friendship Park C45146474641442929392245514728
Houston Bayland Park C53/A146 156555350423434512855664933
Conroe Relocated C78/A321155564555553935703452577334
Manvel Croix Park C8415353525245NVNANANANANANANA
Clinton C403/C304/AH113 353515150392829452152705130
Houston North Wayside C405147504446402929462146755126
Houston Monroe C406148515251433435462550615029
Lang C408250554752453334572751895426
Houston Croquet C409247494748423333472649574628
Houston Westhollow C410/C3003148504546382728402349624429
Park Place C416152545251443435502552725333
Houston Harvard Street C417150524849423233512549785027
Sheldon C5511 N4751NV41372932422446565127
Baytown Wetlands Center C5521 N48484643452827411945514628
Crosby Library C5531 N47504546453133462147615027
West Houston C5541 N49514043362628412250674225
La Porte Sylvan Beach C5561 N49514944453131382145515132
Mercer Arboretum C5571 N50524450433231552646565925
Tom Bass C5581 N52525150443436472655625027
Katy Park C5591 N47474243382518218NVNVNVNA
Atascocita C5601 N47494446442929552343555226
Meyer Park C5611 N52554453443333572849716226
Bunker Hill Village C5621 N50514347403030452451684424
Huffman Wolf Road C5631 N53555051493838532952545531
Wallisville Road C617 1 N53535050503635492852625438
Texas City 34th St. C620 1 N60586257563940473256636242
UH Moody Tower C6951 N535251514534NV532653745128
UH WG Jones Forest C6981 N54574757503737673354597132
Lynchburg Ferry C1015/A165 144514946463135442542554930
Lake Jackson C1016 160585752463535342758555028
Baytown Garth C1017152535151513837492952635638
Galveston 99th St. C1034/A320/X183158576055NV42NV53304958NVNA
UH Smith Point C16061 N51515148503434343349545438
Oyster Creek C1607 1 N606060595341404233585959NA
UH Launch Trailer C16111 N53565054463536522653765126
AreaMonitoring SitePOCApril 2021
San Antonio
San Antonio Northwest C23255654947434047514457724727
Camp Bullis C58 158684947474149544958765124
Calaveras Lake C59152594845413647494260674030
Elm Creek Elementary C5011 N50584541393542453655633922
Fair Oaks Ranch C5021 N50604241413642453846634415
Bulverde Elementary C5031 NNVNANANANV3744504751724516
New Braunfels Airport C5041 N47564242413442434253623922
City of Garden Ridge C5051 N46574241403445484753673922
Seguin Outdoor Learning Center C5061 N49574644413540463950603725
Heritage Middle School C6221 N51574542383344454057633725
CPS Pecan Valley C6781 N46513937332937383448583218
Government Canyon C16101 N48574239373340453548604119
AreaMonitoring SitePOCApril 2021
Corpus Christi-Victoria
Corpus Christi West C4256505042393332343154503622
Corpus Christi Tuloso C21154525144393333383156523321
Victoria C87155525145393333413056593824
AreaMonitoring SitePOCApril 2021
Lower Rio Grande Valley
Mission C43/AP143146544843383444524647463618
Harlingen Teege C1023149524944393436483640342913
AreaMonitoring SitePOCApril 2021
Laredo Vidaurri C44/AFGP144/P244144544541423943504560573423
POC (Parameter Occurrence Code): a code used to correctly separate data from multiple instruments at one site.
NV - There are not enough valid eight-hour averages for this day (there must be eighteen valid eight-hour averages).
NA - Data not available.
 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.