Actually, the air quality is much better now than it was in the 1990s. Based on this 2009 report, combining historic and forecast data,air quality in general i

Actually, the air quality is much better now than it was in the 1990s. Based on this 2009 report, combining historic and forecast data,air quality in general is substantially improved since 1996. Carbon Monoxide, in particular page 4-6 http://www.arb.ca.gov/aqd/almanac/almanac09/pdf/chap409.pdf http://www.arb.ca.gov/aqd/almanac/almanac09/pdf/chap409.pdf