Pollutant-Specific Cautionary Statements
for the Air Quality Index (AQI)
| AQI Category |
Ozone (O3) |
Fine Particles (PM2.5) |
Carbon Monoxide (CO) |
Sulfur Dioxide (SO2) |
|---|---|---|---|---|
| Good | None | None | None | None |
| Moderate | Unusually sensitive individuals should consider limiting prolonged outdoor exertion. |
Unusually sensitive people should consider reducing prolonged or heavy exertion. |
None | None |
| Unhealthy for Sensitive Groups |
Active children and adults, and people with respiratory disease, such as asthma, should limit prolonged outdoor exertion. | People with respiratory or heart disease, the elderly and children should limit prolonged exertion. | People with cardiovascular disease, such as angina, should limit heavy exertion and avoid sources of CO, such as heavy traffic. |
People with asthma should consider reducing exertion outdoors. |
| Unhealthy | Active children and adults, and people with respiratory disease, such as asthma, should avoid prolonged outdoor exertion; everyone else, especially children, should limit prolonged outdoor exertion. | People with respiratory or heart disease, the elderly and children should avoid prolonged exertion; everyone else should limit prolonged exertion. | People with cardiovascular disease, such as angina, should limit moderate exertion and avoid sources of CO, such as heavy traffic. |
Children, asthmatics, and people with heart or lung disease should reduce exertion outdoors. |
| Very Unhealthy | Active children and adults, and people with respiratory disease, such as asthma, should avoid all outdoor exertion; everyone else, especially children, should limit outdoor exertion. | People with respiratory or heart disease, the elderly and children should avoid any outdoor activity; everyone else should avoid prolonged exertion. | People with cardiovascular disease, such as angina, should avoid exertion and sources of CO, such as heavy traffic. | Children, asthmatics, and people with heart or lung disease should avoid outdoor exertion. Everyone else should reduce exertion outdoors. |
| Hazardous | Everyone should avoid all outdoor exertion. | Everyone should avoid any outdoor exertion; people with respiratory or heart disease, the elderly and children should remain indoors. | People with cardiovascular disease, such as angina, should avoid exertion and sources of CO, such as heavy traffic; everyone else should limit heavy exertion. |
Children, asthmatics, and people with heart or lung disease should remain indoors. Everyone else should avoid exertion outdoors. |