Each New England state has seen more days over the last five years when fine particulate matter or ozone exceeds air quality standards that are considered “unhealthy for sensitive groups.”

An air quality alert is in effect for all of Massachusetts as smoke from Canadian wildfires descends into the Boston area.

Large wildfires in remote regions of Canada sent smoke billowing across the border, inundating northern New England with degraded air quality at the beginning of the week.