EPA, States and Tribes Work in Collaboration to Meet the 24-hour Fine Particle National Air Quality Standard
" In an important step to help improve the nation’s air quality, EPA identifies areas across the country that are either meeting or not meeting national standards for fine particle pollution, or PM 2.5.

In response to recommendations from state and tribal representatives, the agency sent letters outlining areas it is considering designating as attainment or nonattainment for the 24-hour fine particle standards. Today, the agency notified 25 states that they currently meet the fine particle standards, while the remaining states have at least one area under consideration for a nonattainment designation. A nonattainment area would include counties with monitors violating the 24-hour standard and near counties that contribute to that violation."