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CORRESPONDENCE Comment on “Speciated Measurements and Calculated Reactivities of Vehicle Exhaust Emissions from Conventional and Reformulated Gasolines” S I R In its study (I),Chevron attempted to understand the influence of gasoline reformulation on emissions. Chevron observed that, on average, non-methane organic gases (NMOG) emissions were reduced by about 6 % when the reformulated gasoline was used and that the average ozone-forming potential (expressed as grams of ozone per gram of NMOG) remained approximately constant. Chevron’s finding on mass emissions appears to be directionally consistent with the results of the AutoIOil (2) or the ARCO (3)studies which have been conducted to investigate the influence of fuel properties on emissions. Chevron’sresults differ in the effects of fuel reformulation on exhaust reactivity. The failure to find a difference in the specific reactivity of the exhaust emissions appears to be due to the differences between Chevron’s baseline reference and reformulated gasolines. The reformulated gasoline used by Chevron is not greatly different from its reference premium gasoline. This is not surprising because the objective of the Chevron program was to examine the influence of only a few gasoline properties on emissions while other studies, such as ARCO’s, investigated the influence of reformulation of eight gasoline properties.
0013-936X/93/0927-1453$04.00/0
0 1993 American Chemical Society
The ARCO reformulated gasoline more closely represents the reformulated gasoline that will be used in California when our Phase 2 reformulated gasoline regulations become effective in 1996. Overall, the results of the Chevron program provide additional confirmation that significant air quality benefits can be achieved with the use of reformulated gasolines. Because of the greater degree of gasoline reformulation that will be required by the Phase 2 regulations in California, air quality benefits will be greater in California than what might be suggested by Chevron’s test results.
Literature Cited (1) Hoekman, S. K. Enuiron Sci. Technol. 1992, 26, 12061216. (2) Hochhauser, A.M.; Benson, J. D.; Burns, V.; Gorse, R. A,; Koehl, W. J.; Painter, L. J.; Rippon, B. H.; Reuter, R. M.; Rutherford, J. A. SAE Tech. Pup. Ser. 1991, No. 912322. (3) Clossey, T. J.; DeJovine, J. M.; McHugh, K. J.; Paulson, D. A.; Rapp, L. A.; Segal, J. S.;Sullivan, B. K.; Townsend, D. J. SAE Tech. Pup. Ser. 1992, No. 920798.
Peter D. Venturlnl
Stationary Source Division California Air Resources Board 2020 L Street P.O. Box 2815 Sacramento, California 958 12
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