State of the air 2009

Source: American Lung Association
"This year marks the tenth annual American Lung Association State of the Air report and provides an excellent opportunity to look back over the changes in the past ten years. This 2009 report looks at ozone and particle pollution year-round (annual average) and over short-term levels (24-hour) of particle pollution (PM2.5) found in monitoring sites across the United States in 2005, 2006, and 2007."