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Map: How bad is the air quality right now?

Smoke from Canadian wildfires blankets downtown Boston
Smoke from Canadian wildfires blankets downtown Boston. (Randy Vazquez/ Globe Staff)

Smoke from Canadian wildfires has been affecting air quality levels in the Northeast, reaching unhealthy levels in many parts of New England.

When small particulate matter in the air reaches certain levels, it can cause health problems for “sensitive groups,” which the MassDEP defines as including “people with heart or lung disease, such as asthma, older adults, children, teenagers, and people who are active outdoors.”

Below, see air quality index readings from around the Northeast and the United States.

What the AQI means

The Air Quality Index is the Environmental Protection Agency’s index for reporting air quality. The index ranges from 0 to 500, with higher values representing higher concentrations of air pollution. The AQI is divided into six categories with individual levels of concern:


  • 0-50 (Good): Air quality is satisfactory, and air pollution poses little or no risk.
  • 51-100 (Moderate): Air quality is acceptable. However, there may be a risk for some people, particularly those who are unusually sensitive to air pollution.
  • 101-150 (Unhealthy for sensitive groups): Members of sensitive groups may experience health effects. The general public is less likely to be affected.
  • 151-200 (Unhealthy): Some members of the general public may experience health effects; members of sensitive groups may experience more serious health effects.
  • 201-300 (Very unhealthy): Health alert. The risk of health effects is increased for everyone.
  • 301+ (Hazardous): Health warning of emergency conditions. Everyone is more likely to be affected.

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John Hancock can be reached at Follow him @Hancock_JohnD.