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How to Properly Use Respiratory Protection

While use of respiratory protection in hazardous atmospheres is the norm, there are still many misconceptions surrounding the use of respiratory protection.

Vince McLeod, CIH

Vince McLeod is an American Board of Industrial Hygiene-certified industrial hygienist and the senior industrial hygienist with Ascend Environmental + Health Hygiene LLC in Winter Garden, Florida. He has more...

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Respiratory Protection Basics

Early in our careers, the Safety Guys were called on to assist with a fire in a feed and fertilizer store in Gainesville, Florida, where we lived and worked. The large fire generated massive quantities of smoke, and police were called in to assist with cordoning off and securing the area. Many of the officers who were stationed downwind ended up with significant symptoms of chemical exposure through inhalation of the smoke from the burning agricultural products. Some of our fire service personnel referred, jokingly, to these perimeter officers as the “blue canaries,” demonstrating the boundary where use of respiratory protection was needed. Shortly after this fire, we were asked to help set up a respiratory protection program for the police department. To the best of our knowledge, the department didn’t have a single functional respirator available at the time of the fire.

Things have come a long way since then, and use of respiratory protection in hazardous atmospheres is the norm. Yet there are still many misunderstandings and misconceptions surrounding the use of respiratory protection. Whether it is about responding to a possible chemical spill incident in the lab, processing chemical wastes, working in a confined space, or just dealing with routine chemical storage in the course of normal activities, we often get questions on the proper use of respirators. So, let’s get started and begin at the beginning.

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First a few words on OSHA regulations regarding respirator use.

There are two basic OSHA requirements: (1) no one may use a respirator unless they are first provided a medical evaluation, and (2) the respirator must be tested on the person to ensure it will actually fit to provide protection. Before ever putting a respirator on, OSHA requires (and it makes good sense) that users ensure they 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.” It goes on to say, “Employees that use any respirators including respirators such as air-supplied positive-pressure face masks or hoods must have a medical evaluation before use.”1

Next, the employer must also ensure that the respirator fits the wearer. A respirator that does not fit properly simply gives the false impression of protection and may be more dangerous than no respirator at all. There are specific fit-test protocols that are accepted by OSHA. The following is an excerpt from an 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 addition, 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. Suffice it to say, if your organization is using respirators, you should have a written program and an administrator well-versed in this OSHA standard.

Respirator basics

Respirators are designed to prevent contaminated air from entering the body. There are several basic face piece designs. Typically one sees “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.

Related Article: Respirator Change Schedule

Respirators can protect the user in two basic ways. The first is by cleaning “dirty” outside air that passes through a filter or 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 can either be delivered via a supply line (supplied-air respirators, aka SARs) or be packaged and carried with you in a tank (self-contained breathing apparatus or SCBA) like a scuba diver.

When using air-purifying respirators, one must first have a good idea of the nature and concentration of the contaminants against which one needs protection. For example, are you seeking protection against actual chemical hazards or simply avoiding exposure to unpleasant odors? In addition, 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, air-purifying respirators should only be used for materials 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” (ESLIs) or establishing cartridge change-out schedules to reduce the likelihood of contaminant breakthrough. These schedules 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 these change-out schedules. A certified industrial hygienist (CIH) can conduct exposure assessments to determine contaminant levels and establish change-out criteria through actual sampling of representative processes.

Related Article: Hidden Dangers in the Air We Breathe

We must emphasize that respirators only reduce the amount of contaminants within the breathing air but don’t eliminate them altogether. Each type of respirator carries an “Assigned Protection Factor” that can be considered as the theoretical amount of protection a properly fitted respirator might provide. The highest protection factor for air-purifying respirators 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 (IDLH), the use of supplied air or SCBA is required. The norm today is the pressure-demand type regulator, because these provide much better protection than the dated 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 rush out of the mask, preventing the entry of any contaminants. The use of SCBA is required for initial entry into a situation where there are unknown concentrations of chemical hazards that may be present.2

Respirators allow us to go where we could not normally enter safely. The use of respirators should not be taken lightly or in a cavalier manner. When used improperly, they can put people in considerable jeopardy. Remember, respirators should only be used as a “last line of defense” when other control systems, such as adequate ventilation or hazard containment, are not feasible.


1. Respiratory Protection, US Department of Labor, Occupational Safety and Health Administration. Washington, D.C. June 2011. 

2. Immediately Dangerous to Life or Health. National Institute of Occupational Safety and Health, Centers for Disease Control. Atlanta, GA. December 2014.