Residents living across a swathe of Minnesota have been warned of potentially dangerous air pollution, with “sensitive” groups urged to stay inside on Memorial Day.

The U.S. Environmental Protection Agency’s (EPA) AirNow map, which offers a real-time snapshot of air quality, showed several areas around Minneapolis shaded orange on Monday. This means that air quality is “unhealthy for sensitive groups,” such as those with asthma or heart conditions.

The areas covered by the orange warning include Minneapolis, Faribault, Lakeville, Maple Grove, Minnetonka, Eden Prairie, and the Minnesota Valley National Wildlife Refuge.

Minnesota has been beset by wildfires over the weekend, adding misery to the devastation already caused by a string of blazes earlier this month that consumed more than 35,000 acres of land.

The Minnesota Pollution Control Agency released a forecast in the early hours of Memorial Day, stating: “Upper-level winds will become southerly on Monday and cut off the transport of any additional smoke to the state. However, high pressure will still hold in place and winds at the surface will remain light.

“Ground-level smoke that impacted northern and central Minnesota over the weekend may linger on Monday. Air quality in the Yellow (moderate) category may continue for this part of the state. Light southerly winds should develop by Tuesday and smoke should begin to disperse and push back to the north. Air quality should improve back into the Green category statewide on Tuesday.”

The EPA said: “Smoke is made up of a complex mixture of gases and fine particles produced when wood and other organic materials burn. The biggest health threat from smoke is from fine particles. These microscopic particles can get into your eyes and respiratory system – whether you are outdoors or indoors, where they can cause health problems such as burning eyes, runny nose, and illnesses such as bronchitis. Fine particles can also aggravate chronic heart and lung diseases – and even are linked to premature deaths in people with these conditions.”

The agency added that wildfire smoke “can make the outdoor air unhealthy to breathe,” and officials usually advise people “to stay indoors during a smoke event” where the air should be safer.

This is a breaking story. More to follow.