Air Quality Index

The Air Quality Index (AQI) is an index used for reporting forecasted and daily air quality. The AQI uses both a color-coded and numerical scale to report how clean or polluted the air is and what associated health effects might be of concern. The AQI focuses on health effects people may experience within a few hours or days after breathing polluted air. EPA calculates the AQI for 5 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. For each of these pollutants, EPA has established national air quality standards to protect public health. Ground-level ozone and airborne particles are the 2 pollutants that pose the greatest threat to human health in this country.

Air Quality Index Chart
Air Quality Index Levels of Health Concern Numerical Value Meaning
0-50 Air quality is considered good, and air pollution poses little or no risk.
Moderate 51-100 Air quality may pose a moderate health risk, especially for those who are unusually sensitive to air pollution.
Unhealthy for Sensitive Groups
101-150 Members of sensitive groups, children and adults with respiratory and heart ailments, may experience health effects and should limit time spent outside. The general public is not likely to be affected.
151-200 Everyone may experience health effects and should limit their outdoor activity. Members of sensitive groups may experience more serious health effects.
Very Unhealthy
201-300 Everyone may experience more serious health effects and should avoid outdoor activities, especially individuals with heart and breathing ailments, children, and older adults.

Air Quality Action Guide
Your "How to" guide for cleaner air, from the Clean Air Partners.
Air Quality Rating Steps to Protect Your Health & Our Environment
Good (0-50)
Enjoy the great outdoors:
  • Rather than drive, bike or walk to work when possible.
  • Conserve energy. Replace incandescent bulbs with CFLs.
  • Plant a tree to improve health and air quality.
Moderate (51-100)
Some pollution. Even moderate levels pose risks to highly sensitive groups:
  • Bundle errands. Eliminate unnecessary trips.
  • Check AirAlerts to see if tomorrow's forecast is unhealthy.
  • Perform regular maintenance on your car.
Unhealthy for Sensitive Groups (101-150)
Pollution levels are harmful to children, older adults, and anyone with a respiratory or heart condition. Limit physical outdoor activity:
  • Don't drive alone. Carpool or take public transit.
  • Refuel your car in the evening.
  • Put off lawn care until air quality improves.
  • Use a gas or electric grill instead of charcoal.
Unhealthy (151-200)
Everyone should limit strenuous outdoor activity when the air is unhealthy to breathe:
  • Telework and take public transit.
  • Turn off lights and electronics when not in use.
  • Avoid lawn mowing or use an electric mower.
  • Sign up for health alerts.
  • Don't use chemicals on your lawn and garden.
Very Unhealthy (201-300)
Pollution levels are very unhealthy for everyone:
  • Avoid any physical outdoor activity.
  • Follow all of the action steps above.

Do Your Share for Cleaner Air
Visit Clean Air Partners to get your daily AirAlerts and discover simple steps you can take each day to improve our region's air quality, protect your health, and reduce the risks of climate change.