Project at a Glance
Title: Development and improvement of organic compound emission inventories for California
Principal Investigator / Author(s): Rogozen, Michael
Contractor: Science Applications International Corporation
Contract Number: A0-101-32
Research Program Area: Atmospheric Processes
The objectives of this study were to (1) review the 1979 statewide organic solvent emission inventory for accuracy and completeness; (2) perform a market balance on the most important solvent species; (3) evaluate the procedures used by the ARB and local agencies to obtain, process and interpret solvent emissions data; (4) develop methods for upgrading the statewide emission inventory; (5) and update and improve those portions of the statewide emission inventory corresponding to solvent use in the South Coast and Bay Area Air Quality Management Districts.
A survey of 114 large solvent-using firms was conducted to verify information presently in the ARB's Emission Data System (EDS) for 1979. Addresses were missing, incorrect or incomplete for 24 percent of the respondents. Standard Industrial Classification (SIC) codes were incorrect for 12 of the 49 respondents. Devices and processes were missing from the records for a significant number of firms. EDS classifications for processes were incorrect for about half the firms responding. Except for cases of devices and processes which were improperly included or omitted, these misclassification problems are not likely to lead to serious errors. They do, however, make it extremely difficult to obtain useful information on emissions of individual solvents or on emissions from particular industries or processes. The failure to take emission abatement devices into account resulted in a 117-ton per year overestimate of total organic gas (TOG) emissions from two facilities. The geometric mean positive and negative discrepancies between EDS values and our emission estimates were 11.1 and 1.8 tons/year, respectively. If our estimates are correct, then the EDS overestimates emissions for all the reporting firms by 492 tons/year, or 13.5 percent. Errors in Universal Transverse Mercator coordinates exceed 0.5 km in about half the cases where we verified the location reported in the EDS. (As an expedient and cost-effective measure the UTM coordinates were assigned to facilities by a computer program which resulted in mislocation errors as great as 0.5 km. The ARB considers only the location of major stacks to be critical for modeling purposes.)
The methods used by the ARB to estimate area source emissions from dry cleaning, degreasing, cutback asphalt and road oil use, solvent recycling, domestic solvent use, use of surface coatings, and pesticides application were reviewed. Significant methodological problems were found for dry cleaning, asphalt and domestic solvent use. An improved relationship between dry cleaning emissions and population was determined. A comprehensive survey of asphalt use showed that road oil use and emissions may be correlated with road mileage, but that cutback asphalt use and emissions may not be. The emission factor used to estimate domestic solvent uses was judged to be too high.
The solvent composition and national use of a wide variety of formulations such as paints, adhesives, personal care products and household products were determined. Total solvent use and individual species use were apportioned to California, then to each county by several methods developed for the study.
Over 6,500 industrial firms were surveyed to obtain data on purchase, direct use, incorporation in product, recycling and disposal of about 70 solvent species and groups. As a check on our results, producers of all the major solvents of interest were surveyed to obtain data on their sales to California users and distributors. Results from these surveys, along with those of our investigation of indirect solvent use, were scaled up to estimate solvent use and emissions by SIC code, chemical species and county.
Aliphatic hydrocarbons account for 45 percent of all the solvent mass used directly in California industry. Other important solvent classes are ketones, alcohols, chlorinated hydrocarbons, and aromatic hydrocarbons.
The total use of organic solvents in the South Coast, Bay Area, San Diego and San Joaquin Valley air basins in 1980 was between 1.2 and 1.6 billion lb. Direct and indirect use accounted for about 871 Ī 184 and 493 million lb, respectively. The heaviest use of solvents occurs in Southern California. Los Angeles, San Mateo, Alameda, San Diego and Orange Counties have the highest use per county.
From our survey results, we estimate that emissions from solvent use in the four major air basins were between 258,000 and 294,000 tons in 1980. The corresponding EDS estimate for these basins in 1979 falls within this range. Our estimates are higher than the EDS values for the South Coast Air Basin and lower for the other basins. The counties having the highest estimated solvent emissions are Los Angeles, Orange, San Diego, Santa Clara, Alameda and San Bernardino.
For questions regarding research reports, contact: Heather Choi at (916) 322-3893
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