Comparison of the smog forming properties of the exhaust gases from two types of motor fuels using plants as indicators

As part of a general study of the influence of fuel composition on the smog forming potential of exhausts from internal combustion engines, a comparison was made of the effect on growing plants produced by exposure to exhaust gases resulting from the combustion of high and low olefinic fuels under otherwise identical conditions. The two types of fuels were used in a two cylinder four cycle engine operation under normal load. Exhaust gases from this engine, when diluted with filtered air and irradiated with sunlight, produced typical damage on five indicator plants. At low concentration, typical damage was produced by the high olefinic fuel at one-fifth the hydrocarbon concentration required to produce damage with the low olefinic fuel. Atypical symptoms, being further studied, were observed when the low olefinic catalytically reformed fuel was employed.