You Are The Air I Breathe

With the current heat wave, here are the 10 big cities with the best and worst air quality per the Environmental Protection Agency. The EPA tracks pollution in 500 urban areas with its Air Quality Index—a measure of sulfur dioxide, carbon monoxide, nitrogen dioxide, and ozone levels. It then rates the air quality on a spectrum from “good” to “hazardous.” The ranking was based on the largest metropolitan areas with the highest percentage of good air quality days.