Today's Ozone Forecasts

Nine Texas communities are participating in the Ozone Forecast Program:  Austin, Beaumont-Port Arthur, Dallas-Fort Worth, Corpus Christi, Victoria, Houston-Galveston-Brazoria, San Antonio, El Paso-Juarez, and Tyler-Longview-Marshall. The table below provides information about whether Ozone is forecast to reach target levels in the affected area. Information about ozone forecast accuracy and other program statistics are available.

This table also lists the current peak one-hour and eight-hour concentrations and the corresponding Air Quality Index (AQI) rating for ozone for May 21, 2012. These ozone measurements are in parts per billion (ppb). The forecast is updated by 3:00 p.m. each day.

The following Ozone Forecast was updated at 1:14 pm CDT on May 20, 2012.

JanuaryFebruaryMarchAprilMayJuneJulyAugustSeptemberOctoberNovemberDecember   12345678910111213141516171819202122232425262728293031   19961997199819992000200120022003200420052006200720082009201020112012
Metropolitan Area	Ozone Forecast* for May 21, 2012	May 21, 2012 as of 7:11 am CDT
		Peak Ozone Concentrations		Ozone AQI Rating
		One-Hour	Eight-Hour
Houston-Galveston-Brazoria ¹	Yes-Orange	43 ppb	††	**
Beaumont-Port Arthur	No	48 ppb	††	**
Dallas-Fort Worth	No	49 ppb	††	**
Tyler-Longview-Marshall	No	31 ppb	††	**
Austin	No	36 ppb	††	**
San Antonio	No	34 ppb	††	**
Corpus Christi	No	57 ppb	††	**
Victoria	No	32 ppb	††	**
El Paso-Juarez ¹	No	47 ppb	††	**
* Yes - Ozone is forecast to reach the target level.    No - Ozone is not forecast to reach the target level. See table below for terminology and target levels.
†† There are not enough one-hour samples available to create a valid eight-hour sample for this metropolitan area for May 21, 2012.
** There is no AQI associated with one-hour samples that are less than 0.125 ppm (125 ppb).

¹ These metropolitan areas have other, non-TCEQ operated monitors that contribute to the overall forecast assessment of the area. Data from these sites is not included in this table.

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.

Ozone Forecast Terminology and Targets

Metropolitan Area	Ozone Forecast Terminology	Ozone Target Level (ppb)	Ozone Averaging Period
Houston-Galveston-Brazoria	Ozone Watch	76	8-hour
Beaumont-Port Arthur	Ozone Action Day	76	8-hour
Dallas-Fort Worth	Air Pollution Watch-Orange	76	8-hour
	Air Pollution Watch-Red	96	8-hour
	Air Pollution Watch-Purple	116	8-hour
Tyler-Longview-Marshall	Ozone Action Day	76	8-hour
Austin	Air Pollution Watch-Orange	76	8-hour
	Air Pollution Watch-Red	96	8-hour
	Air Pollution Watch-Purple	116	8-hour
San Antonio	Air Quality Health Alert	76	8-hour
Corpus Christi	Ozone Action Day	76	8-hour
Victoria	Ozone Action Day	76	8-hour
El Paso-Juarez	Ozone Action Day	76	8-hour

Interpreting the AQI

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.

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 - 0.059
51 - 100	Not Defined	0.06 - 0.075
101 - 150	0.125 - 0.164	0.076 - 0.095
151 - 200	0.165 - 0.204	0.096 - 0.115
201 - 300	0.205 - 0.404	0.116 - 0.374
301 - 400	0.405 - 0.504	Not Defined
401 - 500	0.505 - 0.604	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. On most days the critical pollutant is ozone.

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.