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Air Quality Index

Air Quality Index

How clean is the air in your metropolitan area? 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.

Interpreting the AQI

Reporting for February 9, 2012 as of 6:11 am CST                  
Metropolitan Area
or
Non-Metropolitan County		Air QualityCritical
Pollutant		Air Quality Index Rating
OzoneCarbon MonoxideSulfur DioxidePM-10
(Std Cond)		PM-2.5
(Lcl Acpt)
1-Hour8-Hour8-Hour24-Hour †24-Hour †24-Hour †
AQIppbAQIppbAQIppmAQIppbAQIug/m3AQIug/m3
Amarillo -- Region 1
Amarillo    Good PM-2.5                     25 7.6
Lubbock -- Region 2
Lubbock    Good PM-2.5                     16 4.9
Abilene -- Region 3
Wichita Falls    Good PM-2.5                     19 5.7
Dallas-Fort Worth -- Region 4
Dallas ¹    Good PM-2.5 * 26   ‡     0 0     30 9.3
Fort Worth-Arlington ¹    Good PM-2.5 * 21   ‡   §         42 13.0
Navarro County    Good PM-2.5 * 24   ‡     0 0     25 7.8
Tyler-Longview-Marshall -- Region 5
Longview-Marshall    Good PM-2.5 * 18   ‡     1 1     33 10.3
Tyler ††   * 22   ‡                
El Paso-Juarez -- Region 6
Brewster County    Good PM-2.5 * 28   ‡             12 3.8
El Paso ¹    Good PM-2.5 * 23   ‡   § 2 1 25 27.3 28 8.6
Jeff Davis County ¹ ††                         §
Juarez ¹ ††   * 11   ‡   §            
Odessa-Midland -- Region 7
Odessa-Midland    Good PM-2.5                     20 6.1
Waco -- Region 9
Killeen-Temple ††   * 10   ‡                
Waco ¹    Good PM-2.5 * 20   ‡   § 0 0     34 10.6
Beaumont-Port Arthur -- Region 10
Beaumont-Port Arthur ¹    Good PM-2.5 * 39   ‡   § 3 2     30 9.2
Austin -- Region 11
Austin-San Marcos ¹    Good PM-2.5 * 14   ‡   §         33 10.3
Fayette County    Good PM-2.5                     32 9.8
Houston-Galveston-Brazoria -- Region 12
Brazoria ††   * 31   ‡                
Galveston-Texas City    Good PM-2.5 * 42   ‡     0 0     33 10.0
Houston ¹    Good PM-2.5 * 34   ‡   § 5 3     44 13.6
San Antonio -- Region 13
San Antonio ¹    Good PM-2.5 * 22   ‡   § 2 1 13 13.6 35 10.6
Corpus Christi-Victoria -- Region 14
Corpus Christi ¹    Good Sulfur Dioxide * 31   ‡     1 1       §
Victoria ††   * 21   ‡                
Lower Rio Grande Valley -- Region 15
Brownsville-Harlingen-San Benito ¹    Good PM-2.5 * 35   ‡   §     13 14.2 41 12.6
McAllen-Edinburg-Mission    Good PM-2.5 * 23   ‡         8 8.5 29 8.9
Laredo -- Region 16
Laredo ¹    Good PM-2.5           §         32 9.8
Maverick County    Good PM-2.5                     30 9.2
PM-10 is measured at standard pressure and temperature conditions.
PM-2.5 Acceptable is measured at local pressure and temperature conditions.
† This is an average since midnight for the current day and does not represent an entire day's worth of data.
†† No AQI has been calculated for this metropolitan area. This can happen early in the morning before enough valid ozone or carbon monoxide hourly samples have been collected to create an eight-hour average and should clear up once enough samples are collected. If there are no measurements for any parameter, this indicates a data collection problem. Once this problem is resolved, the data will be filled in and a AQI will be calculated (if possible).
¹ Not all monitors are reporting for this metropolitan area.
§ No data of this type was collected on February 9, 2012 for this metropolitan area, or there were not enough valid hourly samples collected on this date to meet data completeness requirements of a minimum of 18 valid hourly samples in a day, or there have not been enough valid carbon monoxide hourly samples collected to create an eight-hour average.
‡ There are not enough valid ozone hourly samples accumulated on February 9, 2012 to create eight-hour ozone averages.
* There is no AQI associated with hourly ozone averages less than 0.125 ppm (125 ppb).

PLEASE NOTE:  Data in this table is collected from TCEQ air monitoring sites, local agencies, and private monitoring networks. Site specific information is available for each metropolitan area by clicking on the metropolitan area name. This data has not been verified by the TCEQ or the responsible entity and may change. While this is the most current data, it is not official until it has been certified by the appropriate technical staff. This table is updated hourly. Click here for information about all the monitoring sites.

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 EPAExit.

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		 24hr Sulfur Dioxide
in ppm		 24hr PM-10
in ug/m3		 24hr PM-2.5
in ug/m3
0 - 50 Not Defined 0 - 0.059 0 - 4.4 0 - 0.034 0 - 54 0 - 15.4
51 - 100 Not Defined 0.06 - 0.075 4.5 - 9.4 0.035 - 0.144 55 - 154 15.5 - 40.4
101 - 150 0.125 - 0.164 0.076 - 0.095 9.5 - 12.4 0.145 - 0.224 155 - 254 40.5 - 65.4
151 - 200 0.165 - 0.204 0.096 - 0.115 12.5 - 15.4 0.225 - 0.304 255 - 354 65.5 - 150.4
201 - 300 0.205 - 0.404 0.116 - 0.374 15.5 - 30.4 0.305 - 0.604 355 - 424 150.5 - 250.4
301 - 400 0.405 - 0.504 Not Defined 30.5 - 40.4 0.605 - 0.804 425 - 504 250.5 - 350.4
401 - 500 0.505 - 0.604 Not Defined 40.5 - 50.4 0.805 - 1.004 505 - 604 350.5 - 500.4
500 Not Defined Not Defined Not Defined Not Defined 605 - 4999 500.5 - 999.9

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's for sulfur dioxide, PM-10, and PM-2.5 are based on a 24-hour average sampled from midnight to midnight, and the AQI for carbon monoxide is based on the peak eight-hour running average since midnight. On most days the critical pollutant is ozone. Ozone one-hour average concentrations of 125 ppb or higher exceed the old NAAQS ( AQI rating of 106 or higher). The new NAAQS for ozone is based on eight-hour averages and applies in all areas that are classified as attainment for the old one-hour NAAQS. An eight-hour average of 75 ppb exceeds the new NAAQS for ozone. All areas currently classified as nonattainment for the old one-hour standard will still be required to achieve attainment of the one-hour standard (Houston-Galveston-Brazoria, Dallas-Fort Worth, El Paso, and Beaumont-Port Arthur).

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.


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Last Modified February 09, 2012
©2002-2004 Texas Commission on Environmental Quality.