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.

Canadian wildfires are the cause of an air quality alert that’s in effect for the tri-state area, according to health officials. New York City’s air quality index is at 118 on Tuesday, AirNow’s tracker indicates.

PM2.5 — is expected to push the Air Quality Index over 100, reaching levels unhealthy for sensitive groups, including children, older adults, and people

An air quality advisory is in effect for New York City as smoke from Canadian wildfires continues to impact the region’s air, prompting health warnings.

Smoke from ongoing wildfires across Canada continued to drift into parts of the United States on Wednesday, causing hazy skies and triggering air quality alerts in multiple states across the upper Midwest and Northeast.

As Canada grapples with one of its worst wildfire seasons on record, smoke from the blazes have prompted air quality alerts across the U.S.

Much of Manitoba and Saskatchewan remain under air quality warnings. Environment Canada says wildfire smoke continues to contribute to the very poor air quality in the region and could lead to reduced visibility in the coming days.