Canadian wildfire smoke and a dust plume from Africa could collide over the South this week

A plume of dust originating from Africa’s Sahara Desert is tracking west across the Atlantic Ocean Tuesday and will soon reach parts of the Southeast.

(CNN) — Air quality is taking a hit in parts of the central and eastern United States as smoke from out-of-control wildfires in Canada pours south – but that isn’t the only thing millions of people will notice in the sky this week.

This dust could collide with any lingering smoke in the South this week, potentially causing unhealthy air quality and a hazy, duller sky during the day, bracketed by colorful sunrises and sunsets.

Here’s when to expect the worst of each.

Dangerous smoke is impacting millions in North America

More than 100 wildfires continue to burn out of control across Canada, from British Columbia to Ontario. The provinces of Manitoba and Saskatchewan have seen some of the worst blazes, which have forced thousands of people forced to flee their homes over the last week.

Smoke from those wildfires expanded rapidly over Canada and the US in recent days, stretching over an area of Canada equivalent to double the size of Texas – more than half a million square miles – last Thursday.

That smoke area had doubled in size by Sunday, covering more than 1.2 million square miles in Canada. Heavy smoke also overspread about 750,000 square miles of the US on Sunday.

That’s a huge problem due to some tiny pollutants.

Wildfire smoke contains very dangerous pollutants called PM2.5 that can travel deep into the lungs or enter the bloodstream when inhaled. The minuscule particles can lead to breathing problems like bronchitis and cause inflammation that aggravates diabetes, heart disease and other health conditions.

The smoke is most dangerous in areas where it is thickest and closest to the ground. As of early Tuesday, that includes parts of southern Canada and the Upper Midwest, where trackers show air quality is diminished. Thick smoke can block out the sun and wreak havoc on anyone outdoors with unprotected eyes, noses and throats.

That’s the case in Minneapolis Tuesday morning, where air quality tanked to “very unhealthy” levels, the second worst category, according to AirNow.gov. The city briefly had the second-worst air quality in the world, only behind Kuwait’s Kuwait City. Live cameras showed an incredibly dark, smoky sky partially blocking out the Minneapolis skyline.

Some smoke is also drifting slightly higher in the atmosphere. The higher the smoke travels, the less it affects air quality – but it still makes the sky hazy and shields the sun.

Most of the affected areas in the US aren’t experiencing the worst case smoke scenario. But there’s still some risk to vulnerable populations, like children, as its impact to air quality while lessened, isn’t zero.

Smoke and haze will be noticeable for millions of people in the eastern half of the US Tuesday. It could be hazy at times from Chicago to Upstate New York and as far south as parts of Georgia and Florida.

The haze will linger Wednesday in parts of the Midwest, East and South, and a new wave of thicker smoke could rush into the north-central US as a cold front trudges east.

Smoke from these wildfires will likely keep impacting the US through at least the end of the week, but it’s difficult to pinpoint exactly which areas will experience the worst of it more than a couple days in advance.

Desert dust is on the way

While smoke invades the US from the north, another entity is floating toward the country from the east: Saharan dust. This week’s plume is already visible from space via satellite imagery as it blows over the Atlantic Ocean.

The bulk of the plume is set to reach Florida by early Wednesday and spread over more of the Southeast by Thursday.

Dust and smoke could overlap in some areas, making for an especially hazy or dim sky and poorer air quality than if just one of the two factors was in play.

Like wildfire smoke, dust plumes are composed of small particulate matter that can be hazardous if inhaled – especially for people who already have breathing issues.

As its name suggests, Saharan dust originates in the Sahara Desert, where strong winds blow dust and dry air west out of the region frequently from late spring to early fall.

The dust plumes often attract the most attention during the summer because their dry air can disrupt the formation of tropical systems, like hurricanes. It could also limit the amount of stormy weather in the Southeast this week by the same mechanism. However, if any storms manage to overcome the dry air, the dust and rain could combine to drop a muddy mix over the region.

Dust plumes also create colorful sunrises and sunsets with deeper oranges and reds when the conditions are right.

The size of the plume and where it flows in the atmosphere will change its impacts. This dust plume is thicker than previous bouts of dust in May, but it should thin out the farther it tracks into the US this week.

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