2023 Pa. air quality grades for ozone

The American Lung Association's 2023 State of the Air report grades counties on a three-year average of high ozone level days from 2019-2021. Ground-level ozone, which forms from a combination of pollutants and sunlight, can harm the respiratory system. Hover or tap on a county to see its grade, score and the most vulnerable populations compiled in the ALA report.