How does fit testing with an aerosol challenge agent relate to protection from gaseous hazards?
A mask that fits well enough to stop aerosol leaks will also fit well enough to protect against gases. One reason that the pass level for a fit test is at least 10 times the protection level that is actually expected is to account for differences between gases and aerosols. If you are not familiar with the relationship between “fit factor”, “assigned protection factor”, and the safety factor of 10 that is used, refer to TSI Applications Note ITI-023 Fit Factors vs. Protection Factors.
