Effect of Gasoline and Lubricant on Emissions and Mutagenicity of Particles and Semivolatiles in Chain Saw Exhaust

• The exhaust from a two-stroke chain saw engine was characterized using two different types of gasoline, aliphatic gasoline and conventional lead-free gasoline, in combination with four lubricants differing in mineral oil, polyolester, and polyisobutylene (PIB) content. This characterization was focused on emissions of polycyclic aromatic hydrocarbons (PAH) and mutagenicity testing using Ames Salmonella assay. In addition, exhaust emissions of carbon monoxide (CO), nitrogen oxides (NOx), aldehydes, and hydrocarbons (HC) were measured. The two-stroke engine was tested in a test bench, and particulate, semivolatile, and gaseous exhaust components were sampled using a dilution tunnel. Much less PAH were emitted when using aliphatic gasoline due to a much lower gasoline content of PAH and aromatics than the conventional gasoline. Also about half the NOx emissions, up to 50% higher formaldehyde and acetaldehyde emissions, and 10% higher total HC emissions were observed for the aliphatic gasoline. The influence of lubricant on the studied exhaust emissions was found to be of minor importance. In terms of mutagenicity, significant effects were seen for six of the eight gasoline/lubricant combinations, and the highest effects were observed without a metabolizing system. Generally, the conventional gasoline gave higher effects than did the aliphatic gasoline. A difference between lubricants was also seen, especially in combination with gasoline A; however, the interpretation of mutagenic effects of the lubricants was not straightforward. Overall, one synthetic ester-based lubricant and one mineral oil-based lubricant gave the highest mutagenicity.

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