"Overall, the National Academy of Sciences (NAS) report is a decent discussion of the public health challenges and complexities related to controlling air pollution. I took away the message that while there has been significant progress under the Clean Air Act to date, our system could and should be improved in a thoughtful manner to continue reducing emissions as quickly as possible. In particular, the report suggests three important things to me - 1) EPA must be far more forceful in requiring states and sources to reduce pollution that causes problems downwind, especially pollution that comes from older, dirtier sources, 2) conventional pollutants, like ozone and fine particulate matter, and air toxics pose a greater threat to vulnerable populations at every concentration than currently assumed, and, 3) global warming effects should be considered when designing multi-pollutant legislation and air quality regulations."