For most laboratories, respirators would not be a piece of standard equipment. The reason for this is that respirators, due to their inherent imperfections and problems, should be considered last on the list of means for protecting workers. We should use active measures and infrastructure like fume hoods and local exhaust systems, substitution of less or non-hazardous materials, and finally, administrative controls to minimize or eliminate potential hazards for our employees.
However, situations may arise where respirators are the only effective means for protection. Examples include a chemical spill or fire incident in the lab, processing chemical wastes, working in a confined space, or dealing with routine chemical storage in your normal activities. One other “exception” is using respirators on a temporary basis while other control means are undergoing installation.
There are many misunderstandings and misconceptions surrounding the use of respiratory protection and we often get questions on proper use of respirators. If you fall into this category, continue reading for all the information you need to run a successful respiratory protection program.
Clarity on OSHA regulations regarding respirator use
Following the basic premise we opened with on using all means available to control exposures prior to using respirators, there are two fundamental OSHA requirements: first, anyone that must wear a respirator must be provided and pass a medical evaluation and second, wearers must be fit tested to ensure the respirator provided will actually offer protection.
OSHA requires employers to ensure respirator users are physically capable of wearing a respirator. OSHA 29 CFR 1910.134 states: “The employer shall provide a medical evaluation to determine the employee's ability to use a respirator before the employee is fit tested or required to use the respirator in the workplace.” More importantly, “Employees that use any respirators including respirators such as air supplied positive pressure face masks or hoods must have a medical evaluation before use.”
After the employee passes the medical evaluation, the employer must then demonstrate that the respirator fits the wearer. An ill-fitting respirator will give the false impression of protection. There are specific fit test protocols accepted by OSHA. The following is an excerpt from a recent OSHA compliance directive:
- Respirators must be fit tested.
- A “test atmosphere” must be applied to assess the quality of fit.
- The fit test must be applied to each and every employee required to wear a respirator.
- The fit testing requirement applies to all negative pressure respirators including SINGLE-USE RESPIRATORS.
In essence, anywhere respirators are necessary to protect one’s health against respiratory hazards, OSHA requires development of a respiratory protection program in accordance with 29 CFR 1910.134. If respirators are used on a voluntary basis, fewer program elements are required to prevent hazards associated with respirator misuse. If your organization is using respirators, you should have a written program and an administrator well versed in this OSHA standard.
Respirators are designed to prevent contaminated air from entering the body. There are several basic face piece designs. They are categorized as “half mask” respirators, which cover just the nose and mouth, “full face” respirators, which cover the entire face, and “hood” or “helmet” style respirators, which cover the entire head.
Respirators protect the user in two basic ways. The first is by cleaning “dirty” outside air that passes through a filter, adsorption bed, or both, when one inhales. This type is known as an “air-purifying respirator” (APR). The other main type of respirator protects the user by supplying clean breathing air from a remote source. The clean air is delivered via a supply line (supplied air respirators, aka SARs) or the clean air is packaged and carried with you in a tank (self-contained breathing apparatus, or SCBA) like a scuba diver.
When using APRs, one must first have a good understanding of the nature and concentration of the contaminants from which one needs protection. Is the hazard a chemical vapor or particulate? To purify the air, APRs use absorbent media cartridges for gases, fumes, and vapors and high efficiency filters for solid particulates. Combination cartridges are used for multiple hazards.
Most importantly, one should ensure there is adequate oxygen (at least 19.5 percent by volume) in the air since the APR simply cleans the air and will not provide “extra oxygen.” If there is inadequate oxygen, as one might find in confined spaces, air-purifying respirators cannot be used, and one must use a supplied air type.
For non-particulate contaminants, APRs should only be used for compounds that have good sensory “warning properties” such as odor or irritation. This alerts the user to respirator failure either through seal leakage or cartridge overloading.
OSHA requires use of cartridges/canisters with “end-of-service-life indicators” or establishing cartridge change-out schedules to reduce the likelihood of contaminant breakthrough. Your change-out schedule will vary based on the type of work done, the effort expended by the user, and the nature and concentration of contaminants encountered. The technical assistance group of your respirator manufacturer can help establish appropriate change-out schedules. A certified industrial hygienist (CIH) can conduct exposure assessments to determine contaminant levels and establish changeout criteria through actual sampling of representative processes.
We must emphasize that respirators only reduce the amount of contaminants within the breathing air but don’t eliminate them all together. Each type of respirator carries an “Assigned Protection Factor” which can be considered as the theoretical amount of protection a properly fitted respirator might provide. The highest protection factor for APRs is only 50 according to NIOSH. APRs should only be used in relatively low hazard areas where a single face-respirator seal break might be unpleasant but not dangerous.
For high hazard areas, where atmospheres are oxygen deficient or otherwise immediately dangerous to life and health, the use of supplied air or SCBA is required. The newer pressure-demand type regulators provide much better protection than the outdated simple demand style units. With pressure-demand supplied air, the space within the mask is maintained at a higher pressure than the outside air (the pressure part). Thus, if there is a break in the respirator seal, air should only rush out of the mask preventing the entry of any contaminants. The use of SCBA is required for initial entry into situations where there are unknown concentrations of chemical hazards that may be present.
Remember, respirators should only be used as a “last defense” when other control systems, such as adequate ventilation or hazard containment, are not feasible or are under installation. If respirators are used, follow the OSHA requirements. Make sure you understand the hazards and limitations of respirator use.