The American Lung Association has given Sublette County an F for ozone pollution, underscoring a persistent health danger believed to be caused by gas-field emissions, snow cover, little wind, winter sunshine and other factors. The groupâs annual State of the Air report assembled data on ozone and fine-particulate pollution, two of the most dangerous forms of air contamination, from across the nation. In 149 pages, the association compared pollution levels to federal air-quality standards to come up with grades and rankings. The 2021 report covers the years 2017 to 2019. The news about Sublette County, home to the Jonah and Pinedale Anticline natural-gas fields, was anticipated by some. It is the only rural county in the U.S. to receive the failing grade, the Sublette-based Citizens United for Responsible Energy Development said.