Los Angeles's Air Quality Regulations

Los Angeles air quality has improved in recent years because of new regulations on automobile and plant emissions, but the American Lung Association still ranks the Los Angeles area as the metropolitan region in America most polluted by year-round particles, short-term particles, and ozone. This persistent ranking contrasts with other data on Los Angeles's environmental progress. For example, the number of "exceedance" days in the Los Angeles / Long Beach area of southern California (days tha...