The ozone warning program was initiated in 2000 to issue warnings to the public based on measured levels of ozone in the atmosphere. The initial warning system specifically targeted high ozone levels in the Houston-Galveston-Brazoria, Dallas-Fort Worth, and San Antonio areas. The latest area to be added is the Austin area. Other metropolitan areas will be added in the future.

The following information summarizes the latest ozone warnings available. Click on the area link below to view maps of the current hourly ozone averages measured in that area.

What the Warnings Mean

No Warning
No unhealthy levels of ozone were measured during the previous hour.
• No precautionary actions for adults or children are required.
LEVEL ORANGE
The highest measured levels of ozone during the previous hour 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
The highest measured levels of ozone during the previous hour 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
The highest measured levels of ozone during the previous hour 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).