Air Quality Index (AQI) Scale AQI Range AQI Category AQI Colors 0 - 50 Good 51 - 100 Moderate 101 - 150 Unhealthy for Sensitive Groups 151 - 200 Unhealthy 201 - 300 Very Unhealthy

The AQI is an index for reporting daily air quality. It tells you how clean or polluted your air is, and what associated health concerns you should be aware of. The AQI focuses on health effects that can happen within a few hours or days after breathing polluted air. EPA uses the AQI for five major air pollutants regulated by the Clean Air Act: ground-level ozone, particulate matter, carbon monoxide, sulfur dioxide, and nitrogen dioxide. For each of these pollutants, EPA has established national air quality standards to protect against harmful health. For more information on the Air Quality Index, view EPA's AQI Brochure.