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Panel: Steve Risotto
Media: Alison Lynn

The California Air Toxics “Hot Spots" Information and Assessment Act of 1987 requires facilities to report annual emissions of several hundred listed chemicals. Facilities are prioritized based on the potency, toxicity, and quantity of their emissions, and their proximity to sensitive receptors. High priority facilities must conduct risk assessments. Facilities that are determined to pose a "significant risk" must notify the public and implement a risk reduction and audit plan. 

California has developed its own health-based values to be used by facilities conducting risk assessments. The acute and chronic health-based values are called “reference exposure levels" or RELs. The chronic REL is intended to represent the airborne concentration of a substance to which the general population, including susceptible individuals, may be exposed continuously for a lifetime without significant adverse effects. The acute REL is intended to protect against adverse effects, including irritation, following a one-hour exposure. In addition, California has developed unit risk factors and cancer potency factors for known or suspected carcinogens. While these numbers are sometimes the same as those adopted by the EPA, they often differ from federal health benchmarks. 

California’s local agencies may utilize these RELs in their own regulations. For example, the South Coast Air Quality Management District, which encompasses Los Angeles and surrounding areas, has issued a rule to address the potential risks of air toxics at the permitting stage. Before issuing a permit to construct a new, relocated or modified source, the source applicant must "substantiate to the satisfaction" of the district that emissions from the source doe not exceed a "hazard index" of 1.0. The hazard index is defined as the ratio of the estimated maximum one-hour concentration of the pollutant for a potential maximally exposed individual to the pollutant’s acute REL. 

In addition, California has numerous programs to control emissions of VOCs. One of those programs is based on a concept of relative reactivity, and allows aerosol coating products to contain more total VOCs than would otherwise be allowable provided the overall photochemical reactivity of the product does not exceed a specified relative reactivity. (See discussion of Regulation Based on Relative Photochemical Reactivity.) California also has programs regulating the VOC content of architectural coatings and automotive coatings. Other VOC-reducing programs include those targeted at consumer products, general surface coating and solvent usage, aerospace, can & coil, graphic arts, magnet wire, marine vessels, metal parts & products, motor vehicle assembly lines & refinishing, paper, fabric & film, rubber, plastic & glass coating, screen printing, spray coating and wood products. A summary of the rules that apply in different California localities can be accessed at The consumer products rules can be accessed at


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