Good evening. I'm John Yang. Poor air quality warnings have been posted in the upper Midwest,

advising people with heart or lung disease, older adults, and pregnant people to limit outdoor activities.

The reason is wildfires burning in western Canada, some of them hundreds of miles away.

Meteorologists say that this weekend, the smoke and the fine

particulate matter it carries could reach Oklahoma, Tennessee, and Arkansas. Chris Fultz is a

National Weather Service Central Region Fire Weather Program Manager. The smoke is being lofted into

the air. And with the weather pattern that's in place right now, we've got an area of low pressure, basically just east of Hudson Bay over the Great Lakes, which is bringing that air south.

We also have a ridge of high pressure over the western U.S., which is kind of helping to funnel

that smoke from Canada down through the northern plains and into the Middle Mississippi Valley.

Earlier I spoke with Matthew Capucci, meteorologist at My Radar.

I asked him about the health risks from the smoke.

Well, there are two things I think folks are most likely noticing.

Number one, any time you have this fine particular matter, we call PM2.5 down at ground level,

that's dangerous for elderly vulnerable populations.

That's a big concern over parts of the upper Midwest. Obviously, Canada, where's dangerous for elderly vulnerable populations. That's a big concern

over parts of the upper Midwest, obviously Canada where the wildfires are originating,

but across North Dakota, across much of Minnesota, the entire state of Minnesota,

under an air quality alert right now, which will likely be pushed into early next week,

parts of Michigan, north of Chicago and in Wisconsin, a lot of folks are the upper Midwest

and Great Lakes. Now, when the smoke is up high, causing changes to the light, it's harmless,

but down near the surface, when we're breathing it in, it's really bad. It's like if you were

sitting next to a campfire and breathing that in, you wouldn't want to do that. If I were in North

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