Respirator design may boost risk of sharps injury

Study warns of potential threat to HCW safety

Personal protective equipment used to control one type of occupational hazard may cause a different one, say the authors of a recent pilot study on the effect of high-efficiency particulate air (HEPA) respirators on the occurrence of sharps injuries.

The study focused on the use of HEPAs at seven acute care medical centers operated by the Kaiser Permanente Southern California health maintenance organization. Its purpose was threefold:

• to quantify specific factors believed to increase risks for contaminated sharps injuries;

• to determine whether certain respirator designs affected those factors;

• to assess HCW opinions about the suitability of selected respirators relating to patient care and user compliance criteria.1

In late 1993, the U.S. Occupational Safety and Health Administration (OSHA) issued an enforcement policy mandating the use of National Institute for Occupational Safety and Health (NIOSH) -approved HEPAs for respiratory protection of HCWs performing procedures that placed them at high risk of tuberculosis infection.2 The pilot study was undertaken shortly after that, accounting for the inclusion of HEPA respirators instead of the newer NIOSH-approved N-95 respirators, says Enid K. Eck, RN, MPH, principal author and regional HIV and infectious disease coordinator for Kaiser Permanente Southern California in Pasadena.

HEPAs designed for industry, not health care

Although the less cumbersome N-95s were not evaluated in the study, Eck advises hospitals to examine both respirator types to determine whether the designs of the models used might increase sharps injury risks.

"We were very concerned because most of the HEPA respirators that were out there were designed for industry, not health care, so we were looking at it from a couple of different angles. One was the level of filtration necessary to prevent TB transmission, given that in the instances where nosocomial TB had been transmitted, [HCWs] hadn’t been wearing masks of any description, much less HEPAs. Our infection control group was not convinced we needed to go from nothing directly to HEPAs," Eck explains. "We also were concerned about the physical design of the mask and its tendency to impact the user negatively in terms of their fine motor skills."

Occupational health professionals need to think in terms of "a suite of risks," she emphasizes. "We tend to think that we’ve taken care of bloodborne pathogens, so now let’s move on to TB and we’ll take care of that. But in Southern California and many other parts of the nation, TB and bloodborne pathogens happen to be in the same patient, so we need to think holistically in terms of all the things to take into consideration."

Study targeted three key variables

Often, HCWs wearing HEPAs were increasing their infection risks by adjusting the masks so they could see better, which eliminated respiratory protection, Eck says. She proposes that additional variables must be addressed when respirators are worn by workers who perform complex patient care duties that could expose them to potentially fatal bloodborne pathogens through sharps injuries. Variables targeted in the study included visual field, communication, and range of motion.

"Respirator designs that impair any of these key variables have the potential to increase HCWs’ risk for contaminated sharps injuries," the study notes. "Although not evaluated in this study, the same variables should be assessed in the currently designed N-95 respirators now available for use in healthcare settings."

To assess the variables’ contribution to reported sharps injuries in general, occupational health nurses at seven medical centers of various sizes interviewed all 92 HCWs who reported contaminated sharps injuries during a six-month period. A standardized questionnaire that permitted the HCW to assess the role of each variable was used. Questionnaires were matched with injury reports to determine type of injury, device used, and presence of other variables known to increase sharps injury risks.

Employees were asked the following three questions:

• Do you believe that decreased or impaired communication between you and a patient or you and a coworker may have contributed to this injury?

• Do you believe that decreased or impaired mobility may have contributed to this injury?

• Do you believe that decreased or impaired visibility may have contributed to this injury?

HCWs could choose one of four responses: "Yes, definitely"; "May have played a role"; "No"; or "Do not understand."

More than half (61%) of the interviewed HCWs stated that decreased visibility, communication, or range of motion "definitely" or "may have" contributed to their reported sharps injury. Decreased visibility was identified in 46% of reported injuries as a contributing factor, while impaired communication was a factor in 29% of injuries. Decreased range of motion was implicated as a factor in 15% of reported sharps injuries. Less than 20% of HCWs were wearing some type of mask at the time of the reported injury, and none were wearing HEPA respirators. However, each injured worker who was wearing a mask indicated that visual impairment definitely contributed to his or her injury.

Five respirators evaluated

Because most of the workers indicated that the targeted variables contributed to their injury, five NIOSH-certified respirators were selected for evaluation. All were considered appropriate for the health care environment per OSHA’s 1994 proposed respiratory protection standard.3 Four HEPA respirators (3M 9970 and 3M 6000 from 3M Corp.; Moldex 8000 series, Resposable, from Moldex-Metric Inc.; and Uvex HEPA-Tech 3010, from Uvex Safety LLC) and one dust-mist mask (Tecnol DMR 2010 from Tecnol Inc.) were evaluated for impact on visual field, communication, range of motion, and other user criteria that could affect wearer compliance and patient care.

Six HCWs in different job categories (anesthesia, engineering, infection control, respiratory therapy, and two from nursing), with different physical characteristics and of both genders, were chosen to evaluate the masks. Each variable was measured for each HCW with and without the five respirators.

A licensed speech pathologist and audiology specialist evaluated communication in terms of intelligibility and volume. A licensed optometrist measured visibility in terms of visual field obstructions. A licensed physical therapist measured cervical spine and upper extremity ranges of motion.

User compliance criteria such as comfort, ease of application, temperature and moisture build-up, and ability to see the work area were evaluated by a questionnaire that each HCW completed while wearing each respirator. HCWs also were interviewed about their ability to don other personal protective equipment for preventing blood exposures while wearing the respirators.

Results in the three areas were as follows.


— All HEPA respirators tested obstructed medial and inferior visual fields of two or more of the HCWs.

— The Uvex respirator obstructed visual fields for all HCWs tested.

— Range of impairment for the Uvex respirator in the inferior visual field was 16% to 46%, with an average of 31%, which is "of particular concern," the authors state, "because it may impair the HCWs’ ability to complete successfully, without injury, very common high-risk invasive procedures that involve potential bloodborne pathogens exposures (e.g., drawing blood, starting intravenous fluids, etc.)."


— All HEPAs tested impaired communication by reducing intelligibility or volume.

Range of motion.

— All HEPAs tested adversely affected flexion in the cervical spine and upper extremities.

— The Moldex respirator reduced lateral bending and rotation of the cervical spine and upper-extremity range of motion.

In evaluating user criteria that could affect wearer compliance and patient care, the HCWs rated each HEPA respirator significantly worse than the dust-mist mask in all areas assessed, including comfort, ability to see the work space and to perform tasks, temperature inside the respirator, and ease of communication.

The workers also indicated that they found it difficult to don other personal protective equipment such as full face shields and goggles while wearing HEPA respirators correctly. Even regular eyeglasses could not be adjusted properly to maintain an adequate visual field.

Eck points out that the study was not intended to measure a direct correlation between respirator designs and sharps injuries, but "to demonstrate the plausibility of an interaction between these two important occupational health concerns, bloodborne pathogens and Mycobacterium tuberculosis exposure."

Since the study, Kaiser Permanente’s Southern California medical centers have been using N-95 respirators determined not to obstruct visual fields.

"Other people need to look at the N-95s they’re using and determine if there is any kind of correlation," Eck suggests. "Have they looked at visual field, and is it being impaired? Employers must ask if workers have difficulty using a respirator. Can workers see what they’re doing? Think ‘big picture’ about what else employees will have to be doing while wearing a respirator and if they will be able to do all that safely."

Janine Jagger, PhD, MPH, director of the International Health Care Worker Safety Research and Resource Center at the University of Virginia in Charlottesville, says collecting needlestick data related to workers wearing respirators would be a difficult and lengthy process because relatively few HCWs are wearing masks.

"A more targeted approach that could be used immediately is that when respirators are in use, do an immediate evaluation of procedures that those health care workers will have to carry out to determine if the maximum level of safety precautions are in place," Jagger says. "What procedures are people performing while wearing the respirators? Are they high-hazard [procedures] for needlesticks that are most likely to transmit pathogens, such as placing IVs or drawing blood?"

To minimize the risk of bloodborne pathogens transmission, Jagger suggests hospitals ensure that safer needle devices are available in circumstances presenting additional sharps injury risks.

NIOSH spokesman Fred Blosser notes that although the agency has not specifically examined the possibility that respirator design could increase the likelihood of sharps injuries, written NIOSH recommendations explicitly state that in evaluating a respiratory program’s effectiveness, employers should consult workers periodically about their acceptance of respirators, including discomfort, interference with vision and communication, restriction of movement, and interference with job performance.4

"Those kinds of concerns fall into the area of maintaining a good respiratory protection program," Blosser says.


1. Eck EK, Vannier A. The effect of high-efficiency particulate air respirator design on occupational health: A pilot study balancing risks in the real world. Infect Control Hosp Epidemiol 1997; 18:122-127.

2. Decker MD. OSHA enforcement policy for occupational exposure to tuberculosis. Infect Control Hosp Epidemiol 1993; 14:689-693.

3. Occupational Safety and Health Administration. Respiratory protection. (29 CFR Parts 1910, 1915, 1926.) Fed Reg 1994; 59:58,884-58,956.

4. Bollinger NJ, Schutz RH. NIOSH Guide to Industrial Respiratory Protection. Cincinnati: NIOSH; 1987. n