As of Wednesday, more than 400 wildfires were burning across Canada, leading to air quality alerts − indicators the air is unsafe to breathe for certain people − across much of the eastern U.S.

AirNow and PurpleAir use the Air Quality Index, or A.Q.I., a measure of air quality from 0 to 500 that is composed of six categories, from “good” to “hazardous.”

A combination of high heat, poor air quality, and the threat of severe thunderstorms is bearing down on New York City this weekend, prompting

Unhealthy Air Quality Index level. Red: Indexes in the 151 to 200 range are considered "unhealthy." At this level, any member of the general public becomes susceptible to health effects.

As of Tuesday morning, the Air Quality Index in Milwaukee was between 115 to 120, which falls in the "unhealthy for sensitive groups" category.

TEMPO.CO, Jakarta - Jakarta's air quality on Wednesday, July 23, 2025, ranked second-worst in the world, according to the data from air monitoring site IQAir. The Air Quality Index ( AQI) in the capital recorded a level of 183, indicating unhealthy air conditions.

Canadian wildfire smoke no longer lingers in Michigan as of July 18. Southwest Michigan will experience unhealthy air for sensitive groups on July 21.

The air is full of more pollutants than you might think, including the air that makes its way into your home. Hair, pet dander, pollen, mold, and dust are just a few common contaminants that you could be breathing in on a daily basis.