For the ninth consecutive year, Metro Richmond ranks among the cleanest U.S. regions for healthy air, according to the American Lung Association. The organization’s annual “State of the Air” report found that the region (which includes 13 counties and 4 cities) improved to its best performance for ozone smog and remained unchanged from last year’s best-ever results for both the short-term (daily) and the long-term (year-round) measures of fine particle pollution. The daily measure for particle pollution earned “A” grades for posting zero days high in this pollutant for the ninth consecutive year. And for the 14th straight year, the year-round measure at worst matched the previous...