"The American Lung Association has given Duval County an "F" grade in air quality."
"Breaking it down, the city scores an "F" in both the number of high ozone days and in particle pollution.""The worst air quality? It's Los Angeles. By comparison, the ozone data for Los Angeles indicates a weighted average of 96.5. A failing grade is anything over a 3.3. Jacksonville rates a 7.0."