By Scott Schneider
Laborers Health
& Safety Fund

The question of how well a respirator protects has been a matter of controversy between users and manufacturers for many years.

More than 20 years ago, OSHA recognized the need to update its respirator standard and began the rulemaking process. Although a new standard was finally issued in 1998, OSHA put off setting new assigned protection factors (APFs) for various respirators because of disagreement over the levels at which they should be set.

Now, eight years later, the new APFs have finally been published and they go into effect in November. The big question is: are they protective enough?

Many construction workers have to wear respirators to protect themselves from chemical exposures during welding, torch cutting, painting, waterproofing or cutting concrete and masonry. The government began setting "protection factors" for respirators more than 40 years ago in regulations for the Bureau of Mines.

The most controversial part of the new APFs is the lack of any distinction between traditional rubber (elastomeric) masks with cartridge filters and new paper masks (filtering facepieces) that breathe through the entire mask surface.

Both are given an APF of 10. This decision was based primarily on data from the respirator manufacturers. Labor unions, including the Laborers International Union, and many other groups testified that filtering facepiece masks should only get an APF of 5 because they do not seal as well against the face to keep out contaminants.

A 5 would mean they only protect half as well. Yet, OSHA sided with the manufacturers who have been promoting the filtering facepiece masks which have become a larger share of their business.

Respirators are divided into various categories:

The APF is based on the type of mask and the size. The three sizes are: quarter mask (which only covers the nose and mouth), half mask (which covers the lower half of the face) and full face mask (covering the whole face). The larger the mask, the more protection it offers. However, respirators that pump air into the mask can also come in a loose fitting variety. These do not offer as much protection.

The APF is an estimate of how much protection a respirator provides. A protection factor of 10 means that no more than one-tenth of the contaminants to which the worker is exposed leak into the mask. An APF of 100 means only one percent leakage.

The respirator supplied in various situations is based on the hazard faced (e.g. dust respirators for exposures to dusts and gas and vapor respirators for exposures to gases) and the expected level of exposure. The goal, according to OSHA, is to make sure exposure inside the mask does not get above the OSHA permissible exposure limits (PELs).

The promulgation of new APFs will be useful, particularly in helping companies and workers select the right respirator for the job. However, the real issue will continue to be how well the respirator is used. This is a matter of where and when exposures occur, whether the respirator is in good working order, how it is cleaned and maintained and how well it is fitted when used. Every company must have a comprehensive respirator program.

Schneider's seven deadly sins
of Respirator Assigned Protection Factors (APFs)*

1. APFs assume everyone will use the respirators perfectly every time. If not, protection will be less than promised.
2. To protect correctly the concentration of chemicals outside the mask needs to be known. Normally, that is not the case in construction.
3. APFs are designed to keep the concentration below the OSHA limits. These limits are mostly out-dated and not protective enough.
4. APFs are designed to protect 95 percent of workers to the OSHA limits. About five percent (one in 20) will likely be overexposed, an unacceptably high number.
5. APFs are based on protection from the average concentration over the entire workday. Construction workers often are exposed to very high peak levels which can be way over the APF for short periods of time.
6. APFs are mostly based on studies in simulated work situations. These conditions are not that close to what workers experience on real jobsites every day.
7. APFs are based on measuring contaminants inside the mask compared with outside the mask, not on what workers actually breathe into their lungs.

*Based on testimony by Scott Schneider before the OSHA Expert Review Panel on Respirator APFs in June, 1994.