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

Area	Monitoring Site	POC	April 2021
Area	Monitoring Site	POC	1	2	3	4	5	6	7	8	9	10	11	12	13
Dallas-Fort Worth
	Ft. Worth Northwest C13/AH302	2	54	51	48	45	44	39	49	56	45	46	59	59	29
	Keller C17	2	55	50	47	44	43	36	45	53	44	42	56	58	28
	Frisco C31/C680	1	57	51	53	50	47	39	48	59	42	48	59	66	32
	Midlothian OFW C52/A137	1	58	53	49	47	42	31	48	52	40	48	57	45	30
	Denton Airport South C56/A163/X157	1	54	54	54	47	50	39	47	61	48	46	62	65	30
	Arlington Municipal Airport C61	1	56	52	50	48	45	37	48	55	44	46	58	53	30
	Dallas North No.2 C63/C679	1	54	50	50	48	44	37	48	56	41	46	55	56	29
	Rockwall Heath C69	1	51	48	47	42	40	33	43	52	33	43	49	52	27
	Grapevine Fairway C70/A301/X182	1	53	46	46	43	40	34	45	51	38	42	52	58	29
	Kaufman C71/A304/X071	1	54	49	50	43	40	34	45	53	33	45	48	53	30
	Granbury C73/C681	1	58	57	47	42	43	40	47	48	47	43	57	50	25
	Eagle Mountain Lake C75	1	58	58	53	46	47	42	50	58	49	46	62	64	31
	Parker County C76	1	59	59	49	42	44	41	49	53	52	45	59	56	28
	Cleburne Airport C77/C682	1	59	56	48	46	45	39	49	54	49	46	61	51	33
	Dallas Hinton St. C401/C60/AH161	3	56	46	48	47	43	36	48	53	40	46	54	51	29
	Dallas Executive Airport C402	1	58	52	52	49	44	37	49	55	41	47	57	53	30
	Greenville C1006/A198	1	52	50	49	45	44	36	45	54	34	47	51	56	27
	Pilot Point C1032	1	55	52	56	50	50	40	48	60	43	49	63	61	36
	Italy C1044/A323	1	55	51	48	48	42	35	47	51	40	48	54	47	31
	Corsicana Airport C1051	1	51	48	46	48	44	36	47	52	38	51	53	54	30


Area	Monitoring Site	POC	April 2021
Area	Monitoring Site	POC	1	2	3	4	5	6	7	8	9	10	11	12	13
Tyler-Longview-Marshall
	Longview C19/A127/C644	2	49	49	48	48	43	37	32	52	25	44	49	51	22
	Tyler Airport Relocated C82	1	52	49	48	49	47	NV	52	58	32	49	51	54	30
	Karnack C85/AFHP303	1	48	48	48	52	45	36	26	55	26	42	57	NV	8


Area	Monitoring Site	POC	April 2021
Area	Monitoring Site	POC	1	2	3	4	5	6	7	8	9	10	11	12	13
El Paso-Juarez
	El Paso UTEP C12/A125/X151/G125	2	48	57	54	61	50	51	53	47	53	55	50	43	35
	Ascarate Park SE C37/A332/A172/X159	1	45	49	50	51	44	49	50	42	49	52	47	37	34
	Chamizal C41/AH126	1	40	53	51	57	49	50	52	46	52	53	50	38	29
	Socorro Hueco C49/F312	1	49	53	52	55	51	48	55	50	56	57	53	48	38
	Skyline Park C72	1	47	52	49	56	52	53	53	48	53	54	53	45	36
	Ivanhoe C414/F514	1	47	52	52	53	52	55	54	49	54	56	51	46	35
	Ojo De Agua C1021/FG121/FG221	1	54	60	61	64	42	54	57	52	NA	NA	NA	NA	NA


Area	Monitoring Site	POC	April 2021
Area	Monitoring Site	POC	1	2	3	4	5	6	7	8	9	10	11	12	13
Waco
	Waco Mazanec C1037	1	55	57	48	47	44	37	49	49	43	52	59	42	30
	Temple Georgia C1045	1	58	63	49	48	47	39	49	55	51	52	62	43	31
	Killeen Skylark Field C1047	1	NA	NV	49	44	49	42	51	57	52	51	70	50	31


Area	Monitoring Site	POC	April 2021
Area	Monitoring Site	POC	1	2	3	4	5	6	7	8	9	10	11	12	13
Beaumont-Port Arthur
	Beaumont-Downtown C2/A112/C2002	2	49	52	49	53	47	33	32	50	23	47	52	56	37
	West Orange C9/A141	2	48	50	47	50	46	33	33	53	20	44	50	53	31
	Port Arthur West C28/A128/A228	1	47	51	49	51	50	34	35	50	23	47	54	56	37
	Hamshire C64/C654	1	52	53	50	51	47	33	34	47	24	43	59	55	34
	SETRPC Port Arthur C628	1 ^N	NV	NA	NA	NA	NA	NA	NA	NA	NA	NA	NA	NA	NA
	SETRPC 40 Sabine Pass C640/C1654	1	49	52	49	49	51	34	34	48	23	44	49	53	38
	SETRPC Mauriceville 42 C642/C311/C665	1 ^N	53	54	51	57	51	38	39	58	28	50	50	53	33
	SETRPC 43 Jefferson Co Airport C643	1	53	53	50	50	47	32	33	49	23	47	54	53	34
	Nederland High School C1035	1	50	51	49	51	48	34	34	50	23	48	54	53	33


Area	Monitoring Site	POC	April 2021
Area	Monitoring Site	POC	1	2	3	4	5	6	7	8	9	10	11	12	13
Austin
	Austin North Hills Drive C3/A322	2	53	57	42	46	43	38	45	53	49	54	65	46	27
	Audubon C38	1	54	58	40	43	44	37	46	53	48	52	65	45	20
	Dripping Springs School C614	1 ^N	56	61	35	40	42	35	44	55	50	56	71	42	9
	CAPCOG Lake Georgetown C690	1 ^N	50	55	42	41	42	35	41	51	46	47	61	45	18
	Lockhart C1604	1 ^N	53	56	40	45	40	34	43	48	39	58	63	38	27
	St. Edwards University C1605	1 ^N	49	53	39	42	39	33	41	45	41	52	60	38	23
	CAPCOG Bastrop CAMS1612	1 ^N	44	48	39	39	34	29	34	40	32	47	52	33	25
	CAPCOG Elgin C1613	1 ^N	48	52	35	38	34	28	40	38	32	50	53	34	21
	CAPCOG East Austin C1619	1 ^N	49	54	39	42	41	35	41	47	42	51	60	39	23
	CAPCOG Round Rock Brushy Creek W C1620	1 ^N	49	53	39	41	39	33	38	48	42	48	59	39	21
	CAPCOG San Marcos Staples Road C1675	1 ^N	49	55	39	42	39	33	40	45	41	53	60	38	25


Area	Monitoring Site	POC	April 2021
Area	Monitoring Site	POC	1	2	3	4	5	6	7	8	9	10	11	12	13
Houston-Galveston-Brazoria
	Houston East C1/G316	2	NA	NA	NA	NA	NV	NV	36	53	27	48	76	56	27
	Houston Aldine C8/AF108/X150	2	54	56	50	58	49	37	38	48	29	54	86	63	33
	Channelview C15/AH115	3	48	51	48	48	46	32	32	45	23	51	62	50	29
	Northwest Harris Co. C26/A110/X154	2	49	55	43	53	43	31	34	52	29	47	70	61	26
	Hou.DeerPrk2 C35/235/1001/AFH139FP239	1	51	53	52	49	49	35	35	49	28	53	61	55	32
	Seabrook Friendship Park C45	1	46	47	46	41	44	29	29	39	22	45	51	47	28
	Houston Bayland Park C53/A146	1	56	55	53	50	42	34	34	51	28	55	66	49	33
	Conroe Relocated C78/A321	1	55	56	45	55	55	39	35	70	34	52	57	73	34
	Manvel Croix Park C84	1	53	53	52	52	45	NV	NA	NA	NA	NA	NA	NA	NA
	Clinton C403/C304/AH113	3	53	51	51	50	39	28	29	45	21	52	70	51	30
	Houston North Wayside C405	1	47	50	44	46	40	29	29	46	21	46	75	51	26
	Houston Monroe C406	1	48	51	52	51	43	34	35	46	25	50	61	50	29
	Lang C408	2	50	55	47	52	45	33	34	57	27	51	89	54	26
	Houston Croquet C409	2	47	49	47	48	42	33	33	47	26	49	57	46	28
	Houston Westhollow C410/C3003	1	48	50	45	46	38	27	28	40	23	49	62	44	29
	Park Place C416	1	52	54	52	51	44	34	35	50	25	52	72	53	33
	Houston Harvard Street C417	1	50	52	48	49	42	32	33	51	25	49	78	50	27
	Sheldon C551	1 ^N	47	51	NV	41	37	29	32	42	24	46	56	51	27
	Baytown Wetlands Center C552	1 ^N	48	48	46	43	45	28	27	41	19	45	51	46	28
	Crosby Library C553	1 ^N	47	50	45	46	45	31	33	46	21	47	61	50	27
	West Houston C554	1 ^N	49	51	40	43	36	26	28	41	22	50	67	42	25
	La Porte Sylvan Beach C556	1 ^N	49	51	49	44	45	31	31	38	21	45	51	51	32
	Mercer Arboretum C557	1 ^N	50	52	44	50	43	32	31	55	26	46	56	59	25
	Tom Bass C558	1 ^N	52	52	51	50	44	34	36	47	26	55	62	50	27
	Katy Park C559	1 ^N	47	47	42	43	38	25	18	21	8	NV	NV	NV	NA
	Atascocita C560	1 ^N	47	49	44	46	44	29	29	55	23	43	55	52	26
	Meyer Park C561	1 ^N	52	55	44	53	44	33	33	57	28	49	71	62	26
	Bunker Hill Village C562	1 ^N	50	51	43	47	40	30	30	45	24	51	68	44	24
	Huffman Wolf Road C563	1 ^N	53	55	50	51	49	38	38	53	29	52	54	55	31
	Wallisville Road C617	1 ^N	53	53	50	50	50	36	35	49	28	52	62	54	38
	Texas City 34th St. C620	1 ^N	60	58	62	57	56	39	40	47	32	56	63	62	42
	UH Moody Tower C695	1 ^N	53	52	51	51	45	34	NV	53	26	53	74	51	28
	UH WG Jones Forest C698	1 ^N	54	57	47	57	50	37	37	67	33	54	59	71	32
	Lynchburg Ferry C1015/A165	1	44	51	49	46	46	31	35	44	25	42	55	49	30
	Lake Jackson C1016	1	60	58	57	52	46	35	35	34	27	58	55	50	28
	Baytown Garth C1017	1	52	53	51	51	51	38	37	49	29	52	63	56	38
	Galveston 99th St. C1034/A320/X183	1	58	57	60	55	NV	42	NV	53	30	49	58	NV	NA
	UH Smith Point C1606	1 ^N	51	51	51	48	50	34	34	34	33	49	54	54	38
	Oyster Creek C1607	1 ^N	60	60	60	59	53	41	40	42	33	58	59	59	NA
	UH Launch Trailer C1611	1 ^N	53	56	50	54	46	35	36	52	26	53	76	51	26


Area	Monitoring Site	POC	April 2021
Area	Monitoring Site	POC	1	2	3	4	5	6	7	8	9	10	11	12	13
San Antonio
	San Antonio Northwest C23	2	55	65	49	47	43	40	47	51	44	57	72	47	27
	Camp Bullis C58	1	58	68	49	47	47	41	49	54	49	58	76	51	24
	Calaveras Lake C59	1	52	59	48	45	41	36	47	49	42	60	67	40	30
	Elm Creek Elementary C501	1 ^N	50	58	45	41	39	35	42	45	36	55	63	39	22
	Fair Oaks Ranch C502	1 ^N	50	60	42	41	41	36	42	45	38	46	63	44	15
	Bulverde Elementary C503	1 ^N	NV	NA	NA	NA	NV	37	44	50	47	51	72	45	16
	New Braunfels Airport C504	1 ^N	47	56	42	42	41	34	42	43	42	53	62	39	22
	City of Garden Ridge C505	1 ^N	46	57	42	41	40	34	45	48	47	53	67	39	22
	Seguin Outdoor Learning Center C506	1 ^N	49	57	46	44	41	35	40	46	39	50	60	37	25
	Heritage Middle School C622	1 ^N	51	57	45	42	38	33	44	45	40	57	63	37	25
	CPS Pecan Valley C678	1 ^N	46	51	39	37	33	29	37	38	34	48	58	32	18
	Government Canyon C1610	1 ^N	48	57	42	39	37	33	40	45	35	48	60	41	19


Area	Monitoring Site	POC	April 2021
Area	Monitoring Site	POC	1	2	3	4	5	6	7	8	9	10	11	12	13
Corpus Christi-Victoria
	Corpus Christi West C4	2	56	50	50	42	39	33	32	34	31	54	50	36	22
	Corpus Christi Tuloso C21	1	54	52	51	44	39	33	33	38	31	56	52	33	21
	Victoria C87	1	55	52	51	45	39	33	33	41	30	56	59	38	24


Area	Monitoring Site	POC	April 2021
Area	Monitoring Site	POC	1	2	3	4	5	6	7	8	9	10	11	12	13
Lower Rio Grande Valley
	Mission C43/AP143	1	46	54	48	43	38	34	44	52	46	47	46	36	18
	Harlingen Teege C1023	1	49	52	49	44	39	34	36	48	36	40	34	29	13


Area	Monitoring Site	POC	April 2021
Area	Monitoring Site	POC	1	2	3	4	5	6	7	8	9	10	11	12	13
Laredo
	Laredo Vidaurri C44/AFGP144/P244	1	44	54	45	41	42	39	43	50	45	60	57	34	23


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.

Texas Commission on Environmental Quality

Daily Maximum Eight-Hour Ozone Averages for April 2021

Interpreting the AQI