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, pol yolester, and polyisobutylene (PIB) content. This characterization was focu sed on emissions of polycyclic aromatic hydrocarbons (PAH) and mutagenicity testing using Ames Salmonella assay. In addition, exhaust emissions of car bon monoxide (CO), nitrogen oxides (NOx), aldehydes, and hydrocarbons (HC) were measured. The two-stroke engine was tested in a test bench, and partic ulate, semivolatile, and gaseous exhaust components were sampled using a di lution tunnel. Much less PAH were emitted when using aliphatic gasoline due to a much lower gasoline content of PAH and aromatics than the conventiona l gasoline. Also about half the NOx emissions, up to 50% higher formaldehyd e and acetaldehyde emissions, and 10% higher total HC emissions were observ ed for the aliphatic gasoline. The influence of lubricant on the studied ex haust emissions was found to be of minor importance. In terms of mutagenici ty, significant effects were seen for six of the eight gasoline/lubricant c ombinations, and the highest effects were observed without a metabolizing s ystem. Generally, the conventional gasoline gave higher effects than did th e aliphatic gasoline. A difference between lubricants was also seen, especi ally in combination with gasoline A; however, the interpretation of mutagen ic effects of the lubricants was not straightforward. Overall, one syntheti c ester-based lubricant and one mineral oil-based lubricant gave the highes t mutagenicity.