NEW YORK, NEW YORK - JUNE 7: A person waiting for the subway wears a filtered mask as smoky haze from wildfires in Canada blankets a neighborhood on June 7, 2023 in the Bronx borough of New York City.

SALT LAKE CITY (KTVX) — On Friday, Feb. 4, Salt Lake City reached an air quality index score (AQI) of 154, which the state calls “unhealthy.” But what does that score really mean? According to an ...