It turns out, the industry that pollutes more than any other in Southern California than perhaps petroleum refineries is--Hollywood! According to a recent UCLA report from the Institute of the Environment:
The industry tops hotels, aerospace, and apparel and semiconductor manufacturing in traditional air pollutant emissions in Southern California, according to the study, initially prepared for the Integrated Waste Management Board, and is probably second only to petroleum refineries, for which comparable data were not available. The entertainment industry ranks third in greenhouse gas emissions.
The complete article is here.
The full report from UCLA can be found here.