“Air pollution continues to threaten the lives and health of millions of people in the United States despite great progress since the modern Clean Air Act was first passed in 1970. Even as the nation explores the complex challenges of global warming and energy, air pollution remains widespread and dangerous. 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.”