Most recent regional ozone levels

Houston region hourly ozone data are provided by the Texas Commission on Environmental Quality (TCEQ). Ozone values are scaled to the standard air quality index colors.

The "current" data are actually not quite real-time and may not be accurate at all points on the map.

Data are an average of the previous hour, and it takes 20 to 30 minutes for updated information to appear on the map.

For example, at 12:30 pm, the map may read 12 pm, and it reflects average air pollution values between 11 am and noon. The TCEQ has recently adjusted its display to present data in local time, which will be either standard or daylight savings time depending upon the time of year.

The TCEQ uses only a limited number of monitoring stations to create these animations. Thus, although it may appear that a certain ozone level is found only around a monitoring site, that same ozone concentration may also be found in other areas where no ozone monitoring data is available, but it does not appear on the animation. The program also assumes a certain background level of ozone is found across the region even though higher or lower levels of ozone may exist in areas with no monitors.

This table allows you to select various maps and links to data sets for Houston-region air quality conditions and forecasts. National data are below.

Since most pollution emissions are relatively constant, the major factors affecting day-to-day levels of pollution are:

• local weather conditions;
• major chemical plant or refinery pollution releases; and
• transport of pollution from other areas (especially affecting fine particles).

There are some limited near real-time data available for air toxics from the TCEQ, but these data are not presented in a way that is of much use from a personal or public health perspective.

To access historical air pollution data for the Houston region, the TCEQ provides hourly data by pollutant reports (which also include weather data). More extensive pollution monitoring data archives are also available for download and analysis.

What caused the air pollution?

Major air pollution episodes affecting the Houston region are often analyzed by the TCEQ within a few days, and may include extensive maps identifying the areas where the pollution episode originated as well as other contributing factors.

Most recent national ozone data

National hourly ozone data are provided by the US Environmental Protection Agency. Ozone values are scaled to the standard air quality index colors.

The "current" data are actually not quite real-time and may not be accurate at all points on the map.

Data are updated with data from the previous hour, and it takes 20 to 30 minutes for updated information to appear on the map. Furthermore, these data are presented in Eastern time.

For example, at 12:30 pm Central, the map may read 1 pm Eastern. It actually reflects average air pollution values between 11 am and noon Central.

The EPA uses only a limited number of monitoring stations to create these animations. Thus, although it may appear that a certain ozone level is found only around a monitoring site, that same ozone concentration may also be found in other areas where no ozone monitoring data is available, but it does not appear on the animation.

This table allows you to select various maps and links to data sets for national air quality conditions and forecasts.

Since most pollution emissions are relatively constant, the major factors affecting day-to-day levels of pollution are:

• local weather conditions;
• major chemical plant or refinery pollution releases; and
• transport of pollution from other areas (especially affecting fine particles).

The EPA maintains an air toxics database, but these data are not available in a very timely manner. Analyzing the data requires some skill, but can be useful for understanding long-term exposure to air pollution.