Photochemical reactivities of exhausts from 1966 model automobiles equipped to reduce hydrocarbon emissions.

Abstract

During part of the summer of 1966, a small number of automobiles from the Cincinnati phase of the GSA study were used in a irradiation chamber study. The study was conducted to evaluate the photochemical air pollution potential of representative models of the equipped and unequipped automobiles. Only one set of automobiles, the unequipped Chevelles, produced exhausts capable upon irradiation of forming significant levels of oxidants and PAN. Neither the equipped Chevelles nor any of the Fords or Plymouths, whether equipped or unequipped, produced exhausts having the characteristics necessary to form oxidants or PAN upon irradiation. The eye irritation level reported by the panel upon irradiation of exhausts from unequipped Chevelles was much higher than that produced by the irradiated exhausts from any of the other types of automobiles. Overall, there appears to be a small improvement with respect to eye irritation in comparing equipped with unequipped automobiles. To a large extent, the improvement in the air pollution potential of exhausts from equipped Chevelles compared to the unequipped Chevelles can be attributed to the reduction in the hydrocarbon to nitrogen oxide ratio. The irradiated exhausts from equipped Chevelles, except for aldehyde levels, is about the same in photochemical air pollutionmore » potential as are the exhausts from unequipped Fords and Plymouths. Such irradiation chamber measurements are related to exhaust not hydrocarbon reactivities. Hydrocarbon reactivities can be obtained by direct measurement of reactive and nonreactive hydrocarbons in the automotive emissions. 22 references, 4 tables.« less