California’s dirty air caused more than $193 million in hospital-based medical care from 2005 to 2007 as people sought help for problems such as asthma and pneumonia triggered by elevated pollution levels, according to a new study. While much work has been done previously to catalog the economic impact of air pollution across California, the study is the first to quantify the cost of hospital-based medical care caused by the dirty air.

More info here:
http://www.rand.org/news/press/2010/03/02/

Full report here:
http://www.rand.org/pubs/technical_reports/2010/RAND_TR777.pdf