Respirators are better than ever but have yet to achieve the ideal: locking out airborne contaminants 100 per cent of the time for 100 per cent of wearers. No two faces are alike, and with North America’s increasingly diverse workplace, respirators must fit a growing variety of facial shapes and sizes.

So what causes contaminants to sneak by even the most technologically advanced respirators? Here are some common, ongoing fit-test challenges:

Failing to simulate work conditions. Incident reports commonly reveal that even when the respirator passed a fit test, the conditions under which the test was done did not represent the real work environment. Fit-testers should consider the conditions of the workplace, including temperature extremes, dirtiness of the environment, confinement of the environment, and whether the work is done indoors or outdoors.

This is especially critical in very hazardous work, such as fire services. “Firefighters do their fit testing in smoky rooms, while running on a treadmill, and in various other environmental conditions,” says Dave Shanahan, OH&S standards project manager for the Canadian Standards Association. “I’ve even seen them do fit tests with ice sprayed around the mask.”

The CSA standard Z94.4-02 "Selection, Care and Use of Respirators" is only a guideline, but it advises fit-testers to try to simulate workplace conditions. Sitting in a classroom and trying on a mask is not a true test of what the respirators will really be exposed to.

Improper donning. Failing to read the instructions that come with the respirator often leads to wearing it wrong. Even tightening the straps in the wrong order can affect the fit of the mask. Manufacturers do their best to write clear instructions. Some offer posters, free training and support, yet people still improperly use their respirators. Hierbaum says sometimes the employee neglects to read the instructions, and sometimes it’s the employer who throws them out with the packaging.

Facial hair. People with facial hair (even a five o’clock shadow) simply cannot expect the mask flange to seal to their skin and should not wear respirator masks. The solution? Use an alternative form of protection, such as a hood; work in another area; or shave!

Not keeping up with cleaning and change-out. When a respirator cartridge is used for too long, it fills up with contaminants. Every respiratory protection program should include a cartridge change-out schedule to ensure cartridges don’t exceed their service life expectancy.

Respirators are not the most complicated personal protective equipment out there, but nor are they as simple as they look.

Help is available. Anyone who has questions about fit-testing should contact their respirator supplier or manufacturer, or consult CSA Standard Z94.4-02 for information on the care, maintenance and storage of respirators. A new edition being launched in July 2010 will cover biological substances, bioaerosols and infectious agents, to reflect recent scientific advances in respiratory protection.