This Clean Air Action Plan website reports on many parameters. This glossary tells you what all those parameters mean, and will help you understand the data better.
| Good (0 to 50). Air quality is considered satisfactory, and air pollution poses little or no risk. |
| Moderate (51 to 100). Air quality is acceptable; however, unusually sensitive people should consider limiting prolonged outdoor exertion. |
| Unhealthy for Sensitive Groups (101 to 150). The following groups should limit prolonged or heavy outdoor exertion: People with heart disease, pregnant women, children and older adults, people with lung disease, such as asthma |
| Unhealthy (151 to 200). Everyone may begin to experience some adverse health effects (e.g. difficulty breathing and throat irritation), and members of the sensitive groups may experience more serious effects. The following groups should avoid prolonged time outdoors: People with heart disease, pregnant women, children and older adults, people with lung disease, such as asthma. |
| Very Unhealthy (201 to 300). This would generate a health alert suggesting that everyone may experience more serious health effects. The following groups should avoid all outdoor physical activity: People with heart disease, pregnant women, children and older adults, people with lung disease, such as asthma. Everyone else should avoid prolonged or heavy outdoor activity. |
| "Hazardous" (greater than 300). This would trigger a health warnings of emergency conditions. The entire population is more likely to be affected. Everyone should avoid all physical activity outdoors. |