Air pollution is a critical environmental issue for California, which has some of the nation’s most polluted air basins and also the nation’s most stringent set of state and local air quality standards. This paper reviews my previous work in Lin (2011), in which I examine the effects of agriculture-related local regulations in California on air quality, as measured by the number of exceedances of the CO and NO₂ standards, by exploiting the natural variation in policy among the different air districts in California. Agricultural burning policies and penalty fees reduce the pollution from CO. Other policies such as the prohibition on visible emission, fugitive dust, particulate matter, nitrogen and the reduction of animal matter are correlated with higher levels of CO. Regulations on orchard and citrus heaters have no significant effect on the number of exceedances of the CO and NO₂ standards.