A new outbreak of Canadian wildfires is sending a plume of unhealthy smoke into the US yet again

A recent outbreak of wildfires in western Canada is again sending a plume of unhealthy smoke into the United States.

The smoke is already wafting into the Northern Plains and will spread into the Upper Midwest, including Minnesota, Wisconsin, Upper Michigan and Indiana, where air quality advisories that warn of "unhealthy" levels of smoke are in place through the weekend.

The smoke could also cause issues in Iowa and Illinois, including Chicago, which experienced some of the worst air quality in the world amid heavy smoke in late-June.

This time, the smoke plume is not coming from the Canadian province of Quebec. It is instead funneling across Canada from much further away in the West, so it shouldn't reach the Northeast like it did in early June, when New York City's skies turned an apocalyptic shade of orange.

On Friday, the encroaching smoke dropped air quality in parts of Montana and North Dakota to code red, or unhealthy levels on the Air Quality Index, and to code orange, or unhealthy for sensitive groups, in Minnesota, according to airnow.gov.

Wildfire smoke contains tiny pollutants known as particle matter, or PM 2.5, that can get into the lungs and bloodstream once inhaled. These pollutants most commonly cause difficulty breathing and eye and throat irritation, but have also been linked to more serious long-term health issues like lung cancer, according to the Centers for Disease Control and Prevention.

The plume was birthed from nearly 400 fires sparked in Canada's province of British Columbia in the past week, nearly half of which were started by 51,000 lightning strikes from thunderstorms, the BC Wildfire Service said. Some of those thunderstorms were "dry" or produced inconsequential amounts of rain to help squelch any fires, a dangerous prospect in a province experiencing the worst level of drought.