Abstract
Existing information on tailpipe emissions from the literature has been coupled with previously unpublished data to develop a summary of the effects of fuel composition on emissions. Where data are lacking, effects have been predicted. For fuels of present hydrocarbon composition but without lead antiknocks, there may be some increases in emissions of carbon monoxide (due to increased fuel consumption resulting from lower compression ratios) and aldehydes (due to lead removal), coupled with a decrease in particulates. The decrease in particulates bears little import for the ambient environment, since particulates from automotive exhaust are only a very small portion of total atmospheric particulates. For aromatic-enriched fuels of present-day octane number but without lead antiknocks, there are dramatic increases in reactive hydrocarbons, polynuclear aromatics, and aromatic aldehydes—all of which may be considered detrimental to the environment. The conclusion is that overall fuel factors are such that the elimination of lead antiknock from automotive fuels would not result in environmental improvement and will result in an increase of certain important environmental contaminants.