Ozone is always present in some quantity, the following chart provides information regarding potential health impacts of exposure to certain concentrations of ozone.
Concentration
(parts per billion)
Rating
Effects
Recommendations
0 to 50
Good
Little to no risk even for sensitive groups
No Restrictions
51 to 100
Moderate
Some respiratory problems for sensitive groups
Persons sensitive to ozone may wish to limit outdoor activity
101 to 150
Unhealthy for Sensitive Groups
Problems for persons with heart or lung disease
Active children & adults and persons with heart or lung disease should limit outdoor activity
151 to 200
Unhealthy
Problems for all persons and serious health impacts for sensitive groups
All persons should limit outdoor activity. Children and persons with heart or lung disease should avoid being outdoors for long periods of time.
201 to 300
Very Unhealthy
Serious health impacts for all persons
All persons should avoid being outdoors for long periods of time.
Greater than 300
Hazardous
Life-threatening conditions for all persons
No outdoor exposure.
Source: Texas Commission on Environmental Quality
