Project at a Glance

Title: An inventory of carcinogenic substances released into the ambient air of California : task II

Principal Investigator / Author(s): Roberts, R. M. (Richard Michael), 1924-

Contract Number: A9-140-31

Research Program Area: Health & Exposure

Topic Areas: Health Effects of Air Pollution, Toxic Air Contaminants


The purpose of this research was to examine the significant sources of atmospheric transported carcinogenic emissions from a number of stationary sources in California. In the previous phase of this program substances and sites were identified for study and emissions were estimated based upon the available literature. In this phase principal emissions sources at each site were monitored and analyzed. Emission factors were computed and source and dispersion determined population exposure to the adjacent areas modeling. Concentrations predicted due to plant releases were compared with typical urban levels for each substance. Alternative control measures were described.

Sites measured were a secondary lead smelter (reverberatory furnace system stack), a primary steel mill (coke oven, tar decanter, and cooling tower), an asbestos-cement pipe plant (fiber baghouse and fugitive releases), a secondary lead smelter (reverberatory furnace) and four organic chemical manufacturing plants (stacks, storage tanks, wastewater streams, fugitive sources).

Compounas measured were cadmium, arsenic, polycyclic organic matter, asbestos, carbon tetrachloride, chloroform, perchloroethylene, benzene, and ethylene dichloride.

In general it was found that releases predicted from emissions factors published in the literature overestimated the measured emissions derived from source testiny. Releases from organic chemical manufacturing plants were due principally to storage tanks breathing and working losses. Such sources, although permitted by the local district, were exempt from stringent control requirements either because of their capacity, the fluid vapor pressure or the substance classification. The significance of plant releases was evaluated by computing the resultant incremental population exposure above background. Emissions from three of the four chemical plants were predicted to cause elevated population exposure to a level greater than 50% above typical urban background.

Releases of asbestos from the asbestos-cement pipe plant and arsenic from the secondary lead smelter were predicted not to elevate significantly general ambient concentrations of their respective substances. The presence of five carcinogenic polycyclic aromatic hydrocarbon compounds was identified in the coke oven emissions from the primary steel mill. Their quantitative fractions of total emissions were determined by source measurements and their emission factors developed based upon the observed historical incidence of oven leaks coupled with a release factor per leak. Emissions were predicted to significantly elevate the typical ambient levels for the surrounding area. Although it is anticipated that the primary steel operation (coking) will cease, significant reduction of emissions will occur if the most leakprone coke oven batteries were closed.

Alternative control technology options exist and were delineated for all significant emission sources. Practical regulatory options are suggested including reduction of the minimum size for the requirement of storage tank emission controls.

For questions regarding this research project, including available data and progress status, contact: Research Division staff at (916) 445-0753

Stay involved, sign up with CARB's Research Email Distribution List