Canadian wildfire smoke is drifting into northern Maine on Tuesday.
The Maine Department of Environmental Protection warned that the elevated ground-level particle pollution can make the air unsafe for some groups.
Outside northern Maine, the effects are expected to be more moderate.
That pollution is unlikely to dissipate Tuesday as westerly winds keep up through the afternoon. The department anticipates that smoke lingering in Maine until at least Thursday.
But ozone pollution is expected to remain low Tuesday.
Children, older adults and Mainers with lung or heart disease should avoid strenuous outdoor activity and keep their windows closed.
The particle pollution may cause coughing, shortness of breath, throat irritation or mild chest pain.
Adults who exert themselves outdoors also may notice such symptoms.
The impact will be felt most heavily over northern Maine, while the impact on air quality will be more moderate closer to the coast.
As of last week, there were nearly 300 wildfires burning across Canada, according to the Canadian government.
