Smoke from Canadian wildfires is causing air quality concerns for millions of Americans in the Midwest and Northeast.  Air quality alerts were in effect Tuesday in several states, including Michigan and New York.

Wildfires in Canada are sending heavy smoke across the northern U.S., and New Jersey is experiencing some unhealthy air pollution. The air quality has some Northeasterners wondering, what is the AQI, or Air Quality Index? AQI, or Air Quality Index, is the measure of how healthy or unhealthy the air is.

The smoke floating over the border shared between America and Canada is now impacting air quality in states as far south as Texas, AirNow's data shows. The EPA has declared the air quality in states near the Canadian border as "unhealthy or "unhealthy for sensitive groups."