There are two methods of fit testing - Qualitative and Quantitative.
Full-face respirators require a quantitative fit test; half-face respirators can be tested either qualitative or quantitative.
Qualitative testing with simple kits like these is relatively inexpensive, and testing can be done internally by competent persons. Kits are typically supplied with a hood and/or re-usable vapour chamber, and a test solution. These tests are fast, however this relies on the wearer's subjective response, and so are not as reliable as Quantitative.
Quantitative fit testing involves a direct measurement of particulates, using an ambient particle counting machine. The facial seal is tested through a series of exercises designed to simulate the movements in a workday. The protection factor is calculated and reported for each exercise, with the final protection factor reported being an average of all individual test results.
Fit testing should always be done by "a person who has acquired through training, qualification or experience the knowledge and skills to carry out [fit testing]" - Occupational Health & Safety Regulations.
ABSAFE can do this testing for you at any of our office locations, or at your workplace when it suits you!