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Air Quality Index Report

The U. S. Environmental Protection Agency (EPA) has provided a scale called the Air Quality Index (AQI) for rating air quality. This scale is based on the National Ambient Air Quality Standards (NAAQS) and is described in the Code of Federal Regulations, Part 58, Appendix G. This report is based on the AQI standards. More information on the AQI can be found on the EPA's AirNow web site.

Reporting for December 9, 2023                  
Metropolitan Area
or
Non-Metropolitan County		Air Quality RatingCritical
Pollutant		Air Quality Index
OzoneCarbon MonoxideSulfur DioxideNitrogen DioxidePM-10
(Std Cond)		PM-2.5
(Lcl Acpt)		PM-2.5
(Lcl Cond)
1-Hour8-Hour8-Hour1-Hour1-Hour24-Hour24-Hour24-Hour
AQIppbAQIppbAQIppmAQIppbAQIppbAQIµg/m³ (25° C)AQIµg/m³ LCAQIµg/m³ LC
Amarillo -- Region 1
Amarillo Good PM-2.5             2 1.1             12 2.2
Lubbock -- Region 2
Lubbock Good PM-2.5                             6 1.0
Dallas-Fort Worth -- Region 4
Dallas (1) Good Ozone * 46 39 42   §§3 2.2 16 16.6 16 17.8   §§29 5.2
Fort Worth-Arlington (1) Good Ozone * 38 32 35   §§    11 11.2         15 2.7
Tyler-Longview-Marshall -- Region 5
Longview-Marshall Good Ozone * 39 33 36     1 0.4 2 1.8         26 4.6
Texarkana Good PM-2.5                             20 3.6
Tyler Good Ozone * 38 33 36     2 1.4 1 0.8            
El Paso-Juarez -- Region 6
Brewster County Good PM-2.5                             24 4.3
El Paso (1) Moderate PM-10 * 47 37 40   §§## -0.1 34 36.2 62 77.0 47 8.4 28 5.1
Odessa-Midland -- Region 7
Odessa-Midland Good Sulfur Dioxide             38 26.7             19 3.5
Waco -- Region 9
Bryan-College Station Good PM-2.5                             22 3.9
Killeen-Temple Good Ozone * 37 32 35                     14 2.5
Waco (1) Moderate Sulfur Dioxide * 35 31 33   §§68 49.9         33 6.0    
Beaumont-Port Arthur -- Region 10
Beaumont-Port Arthur (1) Good PM-2.5 * 36 31 33     3 2.0 7 7.9         44 8.0
Austin -- Region 11
Austin-San Marcos (1) Good PM-2.5 * 37 31 34   §§1 0.4 13 14.3 19 20.1     36 6.4
Houston-Galveston-Brazoria -- Region 12
Brazoria Good Ozone * 34 30 32         5 5.2            
Galveston-Texas City Good PM-2.5 * 37 31 34     1 1.0 5 5.5         32 5.7
Houston (1) Moderate PM-2.5 * 41 36 39   §§2 1.6 23 24.2     52 9.4 39 7.0
San Antonio -- Region 13
San Antonio (1) Moderate PM-2.5 * 40 33 36   §§0 0.3 15 15.6 12 13.2 53 10.0 32 5.7
Corpus Christi-Victoria -- Region 14
Corpus Christi Good PM-2.5 * 37 31 34     1 1.0             49 8.8
Victoria Good Ozone * 36 30 32                        
Lower Rio Grande Valley -- Region 15
Brownsville-Harlingen-San Benito (1) Moderate PM-2.5 * 33 29 31                     52 9.5
McAllen-Edinburg-Mission Moderate PM-2.5 * 44 31 34             28 30.7     58 12.8
Laredo -- Region 16
Laredo (1) Good PM-2.5 * 33 27 29   §§                38 6.8
Maverick County Good PM-2.5                             24 4.4
The highest AQI value and associated average (1-hour, 8-hour, or 24-hour) that is responsible for the AQI rating are highlighted bold in the table.
PM-10 is measured at standard pressure and temperature conditions.
PM-2.5 is measured at local pressure and temperature conditions.
(1) - Not all monitors are reporting for this metropolitan area.
§§ - There have been no hourly averages of this parameter collected for December 9, 2023 in this metropolitan area.
* - There is no AQI associated with hourly ozone averages less than 0.125 ppm (125 ppb).
## - No AQI is defined for negative values.

PLEASE NOTE:  Data in this table are collected from air monitoring sites in Texas whose data are reported to EPA. Site-specific information is available for each metropolitan area by clicking on the metropolitan area name. These data have not been verified by the TCEQ or the responsible entity and may change. While these are the most current data, they are not official until they have been certified by the appropriate technical staff. This table is updated hourly. Click here for information about all the monitoring sites.

The table above lists the current peak concentration for the critical pollutant, the corresponding Air Quality Index (AQI) category, and the AQI ratings for each of the NAAQS pollutants that are measured real-time. The critical pollutant is the pollutant with the highest AQI rating measured in the area. The table is updated each hour and covers the period from midnight through the indicated ending time for today's data or from midnight to midnight on other days. Listings are provided for each metropolitan area where pollutant levels are monitored by TCEQ.

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		 8hr Carbon Monoxide
in ppm		 1hr Sulfur Dioxide
in ppm		 24hr Sulfur Dioxide
in ppm		 1hr Nitrogen Dioxide
in ppm		 24hr PM-10
in µg/m³ (25° C)		 24hr PM-2.5
in µg/m³ LC		 24hr PM-2.5
in µg/m³ LC
0 - 50 Not Defined 0 - 0.054 0 - 4.4 0 - 0.035 Not Defined 0 - 0.053 0 - 54 0 - 9.0 0 - 9.0
51 - 100 Not Defined 0.055 - 0.070 4.5 - 9.4 0.036 - 0.075 Not Defined 0.054 - 0.1 55 - 154 9.1 - 35.4 9.1 - 35.4
101 - 150 0.125 - 0.164 0.071 - 0.085 9.5 - 12.4 0.076 - 0.185 Not Defined 0.101 - 0.36 155 - 254 35.5 - 55.4 35.5 - 55.4
151 - 200 0.165 - 0.204 0.086 - 0.105 12.5 - 15.4 0.186 - 0.304 Not Defined 0.361 - 0.649 255 - 354 55.5 - 125.4 55.5 - 125.4
201 - 300 0.205 - 0.404 0.106 - 0.200 15.5 - 30.4 Not Defined 0.305 - 0.604 0.65 - 1.249 355 - 424 125.5 - 225.4 125.5 - 225.4
301 - 400 0.405 - 0.504 Not Defined 30.5 - 40.4 Not Defined 0.605 - 0.804 1.25 - 1.649 425 - 504 225.5 - 350.4 225.5 - 350.4
401 - 500 Not Defined Not Defined 40.5 - 50.4 Not Defined 0.805 - 1.004 1.65 - 2.049 505 - 604 350.5 - 500.4 350.5 - 500.4
500+ Not Defined Not Defined Not Defined Not Defined Not Defined Not Defined Not Defined 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.
  • The AQI for carbon monoxide is based on the peak eight-hour running average since midnight.
  • The AQI for sulfur dioxide is based on the peak one-hour measurement since midnight. There is a secondary NAAQS based on a 24-hour average of sulfur dioxide sampled from midnight to midnight, but this NAAQS has such a high starting point that is is never expected to be reached.
  • The AQI for nitrogen dioxide is based on the peak one-hour measurement since midnight.
  • The AQI for PM-10 is based on a 24-hour average sampled from midnight to midnight.
  • The AQI for PM-2.5 is based on a 24-hour average sampled from midnight to midnight.
  • 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.