Air Quality Conditions for the Houston Region

The Harris County public health notification system provides air quality watches and warnings to the public. This webpage provides additional information to help the public understand what these notifications mean and how people can use them to avoid the health effects of air pollution.

In the Houston region, health officials have identified ozone and fine particulates as the pollutants of concern for public notification. The notifications for these two pollutants are issued differently.

For ozone air pollution, the Texas Commission on Environmental Quality issues both watches and warnings. Because unplanned pollution releases or unusual weather conditions make it exceptionally difficult to predict the level that ozone may reach, the watches are a general notification that weather conditions are likely to be conducive to ozone formation. When there is not an ozone watch in effect, the public is not particularly advised to take any precautionary actions, although individuals should exercise common sense and follow the advice of their doctor since unexpected conditions may develop.

The Texas Commission on Environmental Quality issues air pollution warnings automatically based on measurements at air pollution monitors. Some of these warnings indicate that measured pollution levels have already surpassed the benchmark set by the EPA for unhealthy air quality. On other occasions, the warnings indicate that the TCEQ has tentatively classified pollution levels based on an early indication of unhealthy air quality. This method allows the TCEQ to provide appropriate advice to the public as early as possible as an air pollution episode develops. However, due to sudden changes in weather or other factors, the TCEQ may occasionally reclassify air pollution levels as higher or lower than the category reported in its warning.

Warnings are color-coded based on the US EPA's Air Quality Index to indicate the degree of health risk as follows:

• Level Orange: Ozone levels are considered unhealthy for sensitive groups. Active children and adults as well as people with respiratory disease, such as asthma, should limit prolonged outdoor exertion.
• Level Red: Ozone levels are considered unhealthy. Everyone, especially children, should limit prolonged outdoor exertion. People with respiratory disease, such as asthma, should avoid prolonged outdoor exertion.
• level Purple: Ozone levels are considered very unhealthy. Everyone, especially children, should limit outdoor exertion. People with respiratory disease, such as asthma, should avoid all outdoor exertion and limit exposure by staying inside (air conditioned spaces are best).

In recent years, there have been several dozen days annually when air pollution warnings for ozone were justified.

For fine particulate air pollution , the Harris County Public Health & Environmental Services Department issues fine particulate air pollution watches when the Texas Commission on Environmental Quality forecasts an imminent likelihood that fine particulate air pollution is likely to reach unhealthy levels in the near future. In the Houston region, this typically happens when air pollution from other regions is transported to Houston and combines with locally-generated pollution that is trapped by weather conditions.

Unlike ozone air pollution, fine particulates can reach unhealthy levels at any time of the day. For this reason, and because the health risks of fine particulates in the Houston region are generally experienced over a period longer than a few hours, warnings are not issued for fine particulate air pollution. People are advised to take health precautions whenever a watch is issued based on a personal evaluation of health risk.

• To limit your exposure to fine particulate air pollution, keep doors and windows closed. If cooling is needed, turn your air-conditioner to re-circulate mode in your home and car.

In recent years, there have been only a handful of days when fine particulates reached levels of concern in our region.

Ozone Links

• Map
• General Information
• Sign Up For E-mail Alerts
• About Watches and Warnings
• TCEQ
• EPA
• Exceedance Summary
• TCEQ 8-hr Data
• TCEQ 1-hr Exceedances

 

More Information