The Air Quality Index (AQI) is a color-coded chart for reporting daily air quality. Each color tells you how clean or polluted your air is, and what associated health effects might be a concern for you.
The AQI focuses on health effects you may experience within a few hours or days after breathing polluted air. EPA calculates the AQI for five major air pollutants regulated by the Clean Air Act: ground-level ozone, particle pollution (also known as particulate matter), carbon monoxide, sulfur dioxide, and nitrogen dioxide. Ground-level ozone and fine particulate matter are the two pollutants that pose the greatest threat to public health in North Carolina.