The Occupational Safety & Health Administration (OSHA) offers respirator guidance for healthcare workers in an effort to protect them from airborne contaminants. This and other safety materials are available on the OSHA Web site.

Surgical Masks and Respirators
Although some disposable respirators look similar to surgical masks, it is important that healthcare workers understand the significant functional difference between disposable respirators and surgical masks.

•  Respirators are designed to reduce an individual’s exposure to airborne contaminants, such as particles, gases, or vapors. An air-purifying respirator accomplishes this by filtering the contaminant out of the air before it can be inhaled by the person wearing the respirator. A type of respirator commonly found in healthcare workplaces is the filtering facepiece particulate respirator (often referred to as an “N95”). It is designed to protect against particulate hazards. Since airborne biological agents such as bacteria or viruses are particles, they can be filtered by particulate respirators. To assure a consistent level of performance, the respirator’s filtering efficiency is tested and certified by NIOSH.

•  In comparison, surgical masks are not designed to prevent inhalation of airborne contaminants. Their ability to filter small particles varies greatly and cannot be assured to protect healthcare workers against airborne infectious agents. Instead, their underlying purpose is to prevent contamination of a sterile field or work environment by trapping bacteria and respiratory secretions that are expelled by the wearer (i.e., protecting the patient against infection from the healthcare worker). Surgical masks are also used as a physical barrier to protect the healthcare worker from hazards such as splashes of blood or bodily fluids. When both fluid protection (e.g., blood splashes) and respiratory protection are needed, a “surgical N95” respirator can be used. This respirator is approved by FDA and certified by NIOSH.

Another important difference in protecting healthcare workers from airborne infectious agents is the way respirators and surgical masks fit the user’s face. Respirators are designed to provide a tight seal between the sealing surface of the respirator and the person’s face. A roper seal between the user’s face and the respirator forces inhaled air to be pulled through the respirator’s filter material and not through gaps between the face and respirator. Surgical masks, however, are not designed to seal tightly against the user’s face. During inhalation, potentially contaminated air can pass through gaps between the face and the surgical mask, thus avoiding being pulled through the material of the mask and losing any filtration that it may provide.

When personal protective equipment is necessary to protect against droplet transmission of infectious agents, employees must place a barrier between the source of the droplet (e.g., a sneeze) and their mucosal surfaces. Such protection could include a surgical mask to cover the mouth and nose and safety glasses to cover the eyes. Recent studies show that aerosol penetration through a surgical mask is highly dependent on particle size, mask construction, and breathing flow rate. One study showed that penetration rates for submicron particles could be as high as 80 percent for surgical masks.36 Even relatively unconventional uses (e.g., the wearing of multiple surgical masks) have been shown to be less protective than NIOSH-certified respirators. For example, research has shown that the use of up to five surgical masks worn by volunteers results in particle reduction of only 63 percent for one mask, 74 percent for two masks, 78 percent for three masks, and 82 percent for five masks, compared with a recommended reduction of at least 95 percent for properly fitted N95 respirators.37

To help employers and employees better understand respirators, the following paragraphs discuss   their construction, classification, and use.