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Four Highest 24-Hour PM-2.5 Concentrations in 2020
as of May 24, 2020

Use this form to retrieve the four highest 24-hour PM-2.5 (Local Conditions) Acceptable concentration averages from data collected at TCEQ monitoring sites beginning January 1, 1998 through today. Although this is our most current data, it is not considered official until it has been certified by our technical staff. This information is updated hourly. All times shown are in Local Standard Time.

The table below lists the four highest daily maximum 24-hour PM-2.5 (Local Conditions) Acceptable concentrations measured in 2020 in each community where the TCEQ measures PM-2.5. Concentrations that are rated Moderate or higher are color-highlighted based on the EPA-defined Air Quality Index colors. (See Interpreting the AQI.). All PM-2.5 measurements are in micrograms per cubic meter (local conditions). Sample times correspond to the beginning of the 24-hour average.

Use the selection boxes below to customize this report. You may select a different year or a different report format. If you want to cut and paste data from this web page into another application, such as a spreadsheet, select the comma-delimited format. Click on the Generate Report button once you have made your selections.

YearReport Format
Highlight with AQI colors
AreaMonitoring SitePOCHighestSecond HighestThird HighestFourth Highest
Dallas-Fort Worth
Midlothian OFW C52/A1373 N03/26/202017.503/27/202015.505/21/202014.603/17/202014.3
Kaufman C71/A304/X0713 N01/07/202016.601/08/202014.703/26/202014.305/21/202013.9
Corsicana Airport C10513 N04/08/202015.004/09/202014.403/26/202014.303/03/202014.1
Karnack C85/AFHP3033 N01/08/202033.204/08/202018.705/21/202013.003/27/202012.9
El Paso-Juarez
El Paso UTEP C12/A125/X151/G1253 N02/13/202016.703/27/202013.901/15/202013.901/12/202011.1
Ascarate Park SE C37/A332/A172/X1593 N04/25/202036.005/05/202022.005/01/202021.903/27/202019.4
Socorro Hueco C49/F3123 N03/27/202022.505/05/202020.105/04/202014.601/15/202014.6
Waco Mazanec C10373 N05/21/202011.503/26/202011.505/20/202011.404/08/20209.9
Austin Northwest C3/A3223 N01/14/20209.901/01/20209.601/15/20208.201/06/20207.7
Seabrook Friendship Park C453 N05/12/202016.504/19/202015.104/12/202014.905/13/202014.8
Conroe Relocated C78/A3213 N01/01/202039.404/08/202018.405/20/202017.104/22/202016.6
Clinton C403/C304/AH113 3 N01/01/202041.104/08/202023.303/19/202018.504/19/202017.4
Park Place C4163 N01/01/202042.705/20/202015.205/05/202014.503/14/202013.8
UH West Liberty C6993 N01/01/202021.404/12/202018.804/08/202018.203/25/202017.1
San Antonio
Heritage Middle School C6223 N04/22/202019.704/08/202018.405/21/202017.703/26/202016.0
Palo Alto C6763 N04/22/202019.604/08/202017.705/21/202017.405/20/202015.1
Old Highway 90 C677/A3193 N01/01/202037.404/22/202024.504/08/202023.003/26/202021.8
San Antonio Bulverde Parkway1 N04/08/202019.104/22/202017.603/26/202017.005/21/202015.9
New Braunfels Oak Run Parkway1 N04/08/202018.804/22/202017.903/26/202016.105/20/202015.6
Corpus Christi-Victoria
Dona Park C635/AF199/F2993 N04/24/202020.404/22/202020.404/20/202018.505/20/202017.7
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 24hr PM-2.5
in µg/m³ LC
0 - 50 0 - 12.0
51 - 100 12.1 - 35.4
101 - 150 35.5 - 55.4
151 - 200 55.5 - 150.4
201 - 300 150.5 - 250.4
301 - 400 250.5 - 350.4
401 - 500 350.5 - 500.4
500+ Not Defined
  • The AQI for PM-2.5 is based on a 24-hour average sampled from midnight to 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.