The US AQI (Air Quality Index) is a measurement used to communicate the level of air pollution. It ranges from 0 to 500, with higher values indicating worse air quality.
An AQI of 0–50 is considered "Good." Air quality is satisfactory, and air pollution poses little or no risk.
An AQI of 51–100 is considered "Moderate." Air quality is acceptable; however, some pollutants may be a concern for a small number of sensitive individuals.
An AQI of 101–150 is considered "Unhealthy for Sensitive Groups." Members of sensitive groups, such as children, the elderly, and individuals with respiratory or heart conditions, may experience health effects. The general public is not likely to be affected.
An AQI of 151–200 is considered "Unhealthy." Everyone may begin to experience health effects, and members of sensitive groups may experience more serious effects.
An AQI of 201–300 is considered "Very Unhealthy." Health alert: everyone may experience more serious health effects. It is advised to reduce outdoor activity.
An AQI of 301–500 is considered "Hazardous." Health warning of emergency conditions: the entire population is more likely to be affected. Avoid outdoor activity and stay indoors with windows closed.
The EU AQI (Air Quality Index) is a measurement used to communicate the level of air pollution in the European Union. It is divided into five levels, from "Good" to "Very Poor," based on the concentration of key pollutants.
An AQI of 0–25 is considered "Good." Air quality is excellent, and pollution poses no risk to health.
An AQI of 26–50 is considered "Fair." Air quality is generally acceptable, though a small number of particularly sensitive individuals may experience minor discomfort.
An AQI of 51–75 is considered "Moderate." Air quality is acceptable, but some pollutants could cause a health risk for sensitive individuals, particularly during prolonged exposure.
An AQI of 76–100 is considered "Poor." Air quality may affect health, particularly for sensitive groups, such as individuals with respiratory or cardiovascular conditions.
An AQI above 100 is considered "Very Poor." Air quality poses a significant health risk to the general population. It is advised to reduce outdoor activities and take precautions.