Absence of 14 C in PM2.5 Emissions from Gasohol Combustion in Small Engines.

PM2.5 combustion emissions from small engines (string trimmer and chainsaw) using gasoline containing biogenic ethanol were collected and analyzed for their 14 C content. The sampling methodology was designed to minimize potential bias from organic artifact effects. The 14 C in the PM2.5 emissions was found to be drastically smaller (approximately a factor of 40) than the 14 C amounts measured in the fuels. This suggests that the current method of using 14 C measurements on ambient aerosol to estimate the contribution from fossil fuel combustion will be little affected by increased use of ethanol-containing gasoline. [ABSTRACT FROM AUTHOR]