Breaking down Chicago's "worst in the world" air quality

How it works: In a high-pressure dome, as Chicago had last week, the air gradually descends. If the plume of smoke is 5-10,000 feet above the ground, for example, the air carrying the smoke starts to descend toward us, National Weather Service meteorologist Todd Kluber told Axios.

• The air is moving clockwise from the Northwest, through Canada and into the Great Lakes, putting Chicago smack in the middle of the wind's path.

Reality check: The air quality was terrible here, but it could just be that more sensors were monitoring the air in Chicago than where the fires were happening, Kluber said.

Another big question: Who is the least vulnerable age group for poor air quality and why?

How it works: Poor air quality warnings generally target young children, teens and seniors because "people's lungs keep growing until age about 20-25, so anything in those critical years that can harm and stunt lung development can create problems in a person's later years as there is a long tail of lung capacity decline after that point," Respiratory Health Association's Brian Urbaszewski told Axios.

• Plus: Children tend to breathe about 50% more air per pound of body weight than adults, the EPA notes.

The bottom line: There isn't a specific weather pattern that is more susceptible to poor air quality. It's where the fire originates, and yes, a bit of how the wind is blowing.