Assess your risk, then choose your respirator
Expert advice on evaluating respirators
TB, severe acute respiratory syndrome (SARS), smallpox, monkeypox: Your respiratory protection program needs to take into account the different transmission characteristics of each agent.
"Each disease is different," points out Nancy Bollinger, MS, the deputy director of the health effects laboratory division of the National Institute for Occupational Safety and Health (NIOSH) in Morgantown, WV. "You’ll have to do a risk assessment and determination of what respirator should be worn for each individual disease.
"Is it transmitted through the airborne route? Does it survive the evaporation of the droplet? You have to look at the viability of the organism," she explains. "When you cough or sneeze, you have a droplet. Just because the droplet will evaporate to a droplet nuclei doesn’t necessarily mean you still have an infectious particle."
For example, SARS is transmitted through close contact and surface contamination. Most smallpox outbreaks involved close contact, although there was at least one reported case of nosocomial transmission that appeared to be airborne. TB is transmitted through the air and does not survive on surfaces.
"Smallpox can be deposited on bedclothing or a tissue or whatever else a patient is near," Bollinger says. "It gets on your hands; and if you touch your face, you can get the disease. That’s not true with TB."
CDC’s draft smallpox preparedness guidelines recommend using higher levels of respiratory protection, such as powered air purifying respirators (PAPRs), when performing aerosol-generating procedures with smallpox patients, such as bronchoscopy or intubation.
"When you’re working with something like smallpox, you don’t know the infectious dose," Bollinger adds. "You don’t know the air concentration levels. There are so many unknowns; you can’t base your respiratory protection on tried-and-true methods used in industry."
SARS guidelines state, "The optimal combination of PPE [personal protective equipment] for preventing SARS-CoV transmission during aerosol-generating procedures has not been determined. It is unknown whether these higher levels of protection will further reduce transmission. Factors that should be considered in choosing respirators in this setting include availability, impact on mobility, impact on patient care, potential for exposure to higher levels of aerosolized respiratory secretions, and potential for reusable respirators to serve as fomites for transmission," the guidelines add.
CDC recommends the use of the N95 filtering face-piece respirator as minimum protection for health care workers in close contact with patients with smallpox, SARS, and TB. Health care facilities may choose higher levels of protection, including PAPRs, based on as assessment of the hazards, the CDC says.
"The person who selects the respirator needs to be knowledgeable about what is the minimum amount of respiratory protection that is necessary to protect the worker," says Roy McKay, PhD, director of the occupational pulmonology services program at the University of Cincinnati College of Medicine and a respiratory protection expert.
He offers this basic advice for hospital respiratory protection programs:
• Choose a respirator with good fitting characteristics.
From regular fit-testing, you already may have a good idea about whether your main model and brand fits most users. You also should consider the population you’re fitting. Are they mostly women? You’ll want a respirator that comes in small sizes to fit a smaller face. Does the model come in two or more sizes? One size may fit most of your employees, but you’ll need alternatives to allow for differences in facial features, McKay says.
"Look for the experience and knowledge of their fit-tester to help in that decision-making process," he explains.
• Avoid confusion with too many choices.
You’ll need a balance between respirator selection that will provide a good fit and too many choices that can cause problems, advises McKay. For example, an employee may grab a respirator that wasn’t fit-tested on her or him rather than hunt for the correct model.
There are dozens of manufacturers, brands, and models. You might consider conducting a small pilot evaluation, fit-testing with several different respirators to see which one tends to fit best, McKay continues.
• Buy N95 filtering face-piece respirators that have an exhalation valve.
"It will reduce breathing resistance, make it more comfortable, and make it cooler. Therefore, it’s more comfortable to wear," he says.
In fact, discomfort may lead some health care workers to inadvertently breach infection control as they try to adjust the mask with contaminated hands.
"A filtering face-piece respirator, when it’s fitted properly, is not all that easy to wear. If it’s not comfortable, then people tend to not wear it," McKay adds. "If you don’t wear it, you’re not going to be protected."
• Follow fit-testing protocols.
It may be tempting to cut corners, but fit-testing without following the protocol is no better than not fit-testing at all, he says.
McKay recalls one employee health professional that said her supervisor had asked her to cut back on the protocol to save time.
"You’re supposed to administer the test agent a predetermined number of squeezes for each of seven exercises, while conducting head and breathing maneuvers. Her supervisor had her cut down the number of exercises as well as the number of squeezes so she could finish the protocol faster.
"It falsely increases the number of passes so you can make the statement that this respirator fits when in fact it may not," McKay adds.
Conducting invalid fit tests could have repercussions if an employee became symptomatic despite using the respirator, he says.
"One has to wonder what kind of litigation could potentially occur should the respirator not provide the proper amount of protection," says McKay.
(Editor’s note: For a list of NIOSH-approved N95 filtering face-piece respirators, go to: www.cdc.gov/niosh/npptl/respirators/disp_part/n95list1.html. For a video on TB and respirator use, go to: www.cdc.gov/niosh/docs/video/tb.html. For information on SARS and respirator use, go to: www.cdc.gov/niosh/npptl/respirators/respsars.html. For information on courses on fit-testing and respiratory protection, go to Roy McKay’s web site: www.drmckay.com.)
Reference
1. Centers for Disease Control and Prevention. Public Health Guidance for Community-Level Preparedness and Response to Severe Acute Respiratory Syndrome (SARS) Version 2: Supplement I: Infection Control in Healthcare, Home, and Community Settings. Atlanta; 2003. Web: www.cdc.gov/ncidod/sars/guidance/I/pdf/healthcare.pdf.
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