US AQI – US based Air Quality Index, used by government agencies to communicate to the public how polluted the air currently is or how polluted it is forecast to become. As the AQI increases, an increasingly large percentage of the population is likely to experience increasingly severe adverse health effects. Different countries have their own air quality indices, corresponding to different national air quality standards.
- “Good” AQI is 0 to 50. Air quality is considered satisfactory, and air pollution poses little or no risk.
- “Moderate” AQI is 51 to 100. Air quality is acceptable; however, for some pollutants there may be a moderate health concern for a very small number of people. For example, people who are unusually sensitive to ozone may experience respiratory symptoms.
- “Unhealthy for Sensitive Groups” AQI is 101 to 150. Although general public is not likely to be affected at this AQI range, people with lung disease, older adults and children are at a greater risk from exposure to ozone, whereas persons with heart and lung disease, older adults and children are at greater risk from the presence of particles in the air.
- “Unhealthy” AQI is 151 to 200. Everyone may begin to experience some adverse health effects, and members of the sensitive groups may experience more serious effects.
- “Very Unhealthy” AQI is 201 to 300. This would trigger a health alert signifying that everyone may experience more serious health effects.
- “Hazardous” AQI greater than 300. This would trigger a health warning of emergency conditions. The entire population is more likely to be affected.