The COVID-19 pandemic has underscored the importance of respiratory protection in healthcare settings and in the community. Healthcare workers at high risk of infection need the most effective respiratory protection, and not all surgical masks and respirators are alike. Checking for proper fit, donning and doffing correctly, and following manufacturers’ instructions for use (IFU) are among the practices that can help to reduce the risk of infection transmission.
This article discusses research on respiratory protection and recommendations presented in a webinar by Cori L. Ofstead, MSPH, president and chief executive officer, Ofstead & Associates, St Paul, Minnesota, and Krystina M. Hopkins, MPH, research associate with Ofstead & Associates.
Ofstead, a renowned research epidemiologist, and Hopkins, an expert in environmental health and infectious diseases, explain the different types of surgical masks and respirators and what to consider when choosing respiratory protection. Their webinar can be accessed for free at https://ofstead.elevate.commpartners.com/p/face-mask.
What makes surgical masks different from other disposable masks?
The number one thing, says Ofstead, is they’re regulated by the Food and Drug Administration (FDA) as medical devices. According to regulations, they must be able to resist penetration by fluids, such as blood and body fluids, at a velocity consistent with the intended use of the device.
The surgical face mask looks similar to a procedure mask and may have ties or ear loops. Some of the masks they examined also had a foam pad on the inside along the upper edge that goes over the nose and along the cheeks. The sample of a surgical mask they dissected had three layers. The middle layer’s polypropylene fibers are more densely packed than the outer and inner layers.
Fluid resistance is essential for healthcare workers who may be exposed to body fluids or other liquids, such as water and chemicals used to clean and disinfect or sterilize instruments, Ofstead says.
To evaluate fluid resistance, they squirted the outside of a surgical mask with Glow-Germ. Under normal light, nothing could be seen on the inside of the mask, but under black light, a large area of penetration was seen, along with splatter on the ties (sidebar, “Evaluating fluid resistance: The inside of the surgical mask”).
Ofstead says she and her colleagues were not expecting to see this penetration because the definition of surgical masks requires them to be fluid resistant. “This made us wonder if these standards are being enforced in the field,” she says.
She adds that the splatter on the ties reinforces the recommendation that healthcare workers wash their hands after taking off a mask. “Even if you handle it only by the ear loops or ties, you can get those germs on your hands,” Ofstead says.
The bottom line is, “if you want to confirm that a particular mask or respirator provides fluid resistance, don’t rely solely on the packaging claims—do your own tests to confirm that it offers splash protection,” she says.
There are three primary types of air-purifying respirators:
• Filtering facepiece respirators—commonly called FFR, FFP, N95, or KN95
• Elastomeric facepiece respirators—commonly called elastomerics
• Powered air-purifying respirators—commonly called PAPRs.
N95 respirators. The key features of the N95 respirators include the three Fs:
• Filtration: Their high fiber density provides mechanical filtration, and polypropylene fibers provide the benefit of electrostatic filtration. N95s filter more than 95% of particles that are 0.3 microns or larger.
• Fit: They are intended to make a good seal around the nose and mouth, and to make sure there is a good seal, fit testing and seal checks are required prior to use.
• Fluid resistance: Those classified as surgical N95s are FDA cleared as fluid resistant. However, other N95s and KN95s may not repel splashes or fluids.
It also is important to keep in mind that these respirators are labeled as single-use devices.
Ofstead tore apart Home Depot and 3M models of N95 masks. They each had 5 layers.
A closer look at the 3M N95 finds that it is approved by the National Institute for Occupational Safety and Health (NIOSH), and it has an FDA Emergency Use Authorization (EUA) that allows it to be used by healthcare workers.
It has foam cushioning on the nosepiece, which can make it more comfortable and create a better seal. There are two elastic straps to help secure it on the head. The packaging note says it is not fluid resistant and states clearly that a face shield must be worn during use.
To ensure proper sealing of an N95 against the wearer’s face, the Occupational Safety and Health Administration (OSHA) requires annual fit testing for anyone wearing an N95 respirator for protection at work.
This can be done with a machine to get quantitative results, or it can be done with a taste or smell indicator (qualitative test) to see if the wearer can sense chemicals that taste or smell sweet or bitter, or are irritating, causing a cough when they are inhaled.
Fit testing is specific to the brand, make, and model of the respirator tested. This means an employer should assist employees in deciding on which N95 type and size fits them, and then they should wear only that particular mask.
Ofstead says it is also important to note that over time—because of changes in weight, dental issues, cosmetic surgery, or facial scarring, for example—the N95’s fit may change.
To ensure safety, a wearer should perform a self-seal check when donning the respirator, she says. “This involves securing the N95 to your face, then putting your clean hands on the surface to confirm that it expands slightly when you exhale and caves in slightly when you inhale.”
OSHA regulations prohibit respirator use by workers with facial hair that comes between the face and the sealing surface of the respirator. Beards, sideburns, and some mustaches interfere with the seal, and it has been found that a couple of days’ worth of stubble do the same thing. According to OSHA, facial hair causes 20 to 1,000 times more leakage than a clean-shaven face.
OSHA says gases, vapors, and particles in the air will take the path of least resistance and bypass the part of the respirator that captures or filters hazards out. OSHA also notes that the vast majority of particles, gases, and vapors follow the air stream right through the facial hair and into the respiratory tract of the wearer.
“If you have facial hair and need highly effective personal protection, consider wearing a loose-fitting PAPR because it works without a tight seal, and fit testing is not required,” Ofstead advises.
To evaluate fluid resistance, Ofstead and her colleagues placed a tiny droplet of red dental dye on the surface of the N95, and watched what happened for 15 minutes (sidebar, “Evaluating fluid resistance: Dental dye placed on surface of N95 mask”).
When they took a close look at the way the dye spread, they realized it reached the seam and then traveled along the seam.
Next, they dissected the mask to see how it looked inside, and found the dye bled all along the seam (sidebar, “Evaluating fluid resistance, N95 mask, 15 minutes later”). Looking at the layers of the mask under the microscope, they found the dye had soaked through the outside layer and only the side of the second layer that was next to the outside layer, and it never reached layer three or further through the respirator material.
“Even so,” Ofstead says, “the fact that a tiny droplet soaked through to two layers reinforces the need for a face shield for splash protection. It pays to confirm that surgical masks and N95 respirators are truly fluid resistant before counting on them to protect you from splashes.”
N95 respirators with exhalation valves. Some N95 respirators have exhalation valves, which are built in to make breathing easier by reducing the resistance felt during exhalation. A person’s breath goes through the valve rather than through all the layers of N95 filtering material, which is much easier, and it’s not as hot as an N95 without a valve.
This type of N95 is good for industrial or construction workers, where the goal is to protect them from dust or particulates floating in the air, and there is no concern about what they exhale. The valve allows their breath and droplets to go out the hole into the surrounding environment.
In the context of COVID-19, the Centers for Disease Control and Prevention (CDC) has issued a warning about exhalation valves, saying that “… masks with one-way valves or vents allow air to be exhaled through a hole in the material, which can result in expelled respiratory droplets that can reach others. This type of mask does not prevent the person wearing the mask from transmitting COVID-19 to others. Therefore, the CDC does not recommend using masks for source control if they have an exhalation valve or vent.”
Many institutions have banned these types of respirators because of the risk of transmission.
Elastomeric respirators. Elastomeric respirators look like the gas masks people wear on TV, says Ofstead. They come in a half facepiece with goggles or a whole facepiece that offers splash protection for the eyes.
Filtration is provided by filter cartridges or disc-style filters that may be replaceable, and they offer protection against gases or vapors in addition to particles.
Personal protection is equivalent to or better than that of an N95 respirator. However, source control may be poor because of the exhalation valves that can allow unfiltered air to exit.
The facepieces are generally made of a natural or synthetic rubber that forms to the face. They have adjustable straps that allow them to have a good fit, but annual fit testing is required.
Elastomerics are generally not cleared by the FDA for fluid resistance.
Elastomerics are appealing to a lot of people because they can be cleaned, disinfected, and reused, says Ofstead. However, it’s important to take precautions to avoid getting exposed to pathogens during doffing. Because pathogens can survive on elastomerics for hours to weeks, the respirators need to be cleaned and disinfected before they are stored and reused.
According to CDC guidelines, elastomeric respirators should be cleaned and disinfected immediately after removal. Instructions regarding chemicals and methods vary by manufacturer.
Ofstead says the processes used may cause damage and deterioration of the facepiece materials. If steps are not done correctly, there may be an adverse impact on performance during reuse, she cautions.
The elastomeric filter itself cannot be cleaned or disinfected, so it has to be discarded when it gets soiled, clogged, or damaged. “In fact,” says Ofstead, “manufacturers typically recommend that filter cartridges be discarded after each use when cleaning an elastomeric respirator, but this can be costly, and it’s not always possible.”
Powered-air purifying respirators (PAPRs). A PAPR has a machine that actively filters air and blows clean air into the wearer’s breathing zone. It requires the wearer to carry a machine and battery pack to power the air purifier.
PAPRs offer excellent personal protection with filtration that’s even better than N95s and elastomerics.
The fit depends on the configuration used. Some have tight-fitting facepieces, helmets, or loose-fitting hoods that ensure the wearer is breathing filtered air.
For fluid resistance, some PAPR configurations may protect the wearer from splashes, and others may leave the eyes or parts of the face exposed.
Source control is a different issue with PAPRs, entirely, says Ofstead. Some PAPRs filter exhaled air before it’s returned to the environment, but others allow exhaled air to exit without being filtered. This means they provide excellent protection for the wearer, but they may allow others to be exposed if the wearer is carrying COVID-19 or another respiratory infection.
Practices for donning and doffing PAPRs depend on the product, how it is used, and what else the wearer is wearing. It’s important to refer to the manufacturer’s IFU and government resources.
Like elastomerics, PAPRs have reusable and disposable components, and it’s important to refer to the IFU for specific steps and cleaning products.
It is also important to inspect and reprocess any reusable respirator after each use, says Ofstead.
Historically, face masks have been used by healthcare workers during surgery, says Hopkins.
Source control is important during surgery to protect the patient and keep the sterile field from being contaminated.
• wear a new mask for each surgical procedure
• wear a mask that fits well—covers the mouth and nose and does not vent out the top or sides
• avoid hanging masks around the neck
• wash hands after removing masks.
The CDC has transmission-dependent recommendations depending on whether transmission is by droplet or aerosol.
Droplet precautions include isolating patients in separate rooms or keeping them far apart, and providers should wear surgical masks, which are donned before entering the room.
Aerosol precautions are stricter, and patients should be isolated in negative pressure rooms. Providers should wear N95 respirators or higher, which are donned before entering the room.
The American College of Chest Physicians released guidelines for infection control during bronchoscopy based on risk levels in 2005:
• For low-risk patients, standard personal protective equipment (PPE) is appropriate (gown, gloves, surgical mask, eye protection).
• For medium-risk patients (eg, tuberculosis patients), fit-tested N95 respirators are recommended at a minimum.
• For high-risk patients (eg, 2003 severe acute respiratory syndrome patients), PAPRs are recommended.
PPE is important, but it’s only part of an overall infection prevention and control strategy, says Hopkins.
For the healthcare setting, NIOSH lays out a hierarchy of controls for limiting personnel exposure to hazards. The best case scenario for protecting personnel, she says, would be to either eliminate the hazard or substitute the hazard with a safer option.
“When we are talking about a patient with an infectious disease who needs medical support, however, we can’t just remove or replace that person. Therefore, we have to rely on downstream protections like engineering controls to isolate the hazard, administrative controls to minimize extent of exposure, and use of PPE to protect healthcare workers who must be exposed,” she says.
Engineering controls. The goal with engineering controls is to create a physical environment that reduces risk. During COVID-19, this has included installing physical barriers and encouraging social distancing in areas like waiting rooms.
It also includes improving ventilation, using isolation rooms, increasing air turnover, improving filtration, and spending more time cleaning and disinfecting surfaces.
Administrative controls. Administrative controls involve the establishment of practices and policies that reduce risk. During COVID-19, these policies include shifts to telehealth appointments, preregistration online, limiting visitors, and grouping infectious patients together and having the same staff care for them to limit exposure to others.
Changing guidelines. During COVID-19, guidelines have been changing, which makes it hard to know what to do, says Hopkins. The pandemic also led many providers to wear masks and respirators who had never worn them before. Many don’t have the training and practice to understand how to wear masks properly and why it is so important, she says. Exacerbating those issues were low supplies and poor quality of supplies.
Mask shortages have led to policy changes, including disinfecting, sterilizing, and reusing N95 respirators.
“We have a number of concerns about this approach,” says Hopkins, “including the fact that filtering materials are designed to trap everything that flows through them, and the N95 respirators can’t be cleaned before disinfection and sterilization.
“We know from our experience with endoscope reprocessing that cleaning is a key factor in the success of disinfection and sterilization processes,” she says. “We also are worried about occupational health risks for healthcare workers who may be exposed to residual chemicals when they wear reprocessed N95s.”
Numerous adverse event reports have been submitted to the FDA pertaining to injuries from N95s that have been reprocessed with hydrogen peroxide, including respiratory issues like coughing, shortness of breath, chest tightness, sneezing, runny nose, and irritated throat. Also reported are chemical burns, hives, and neurological issues like headaches and nausea from residual reprocessing chemicals.
COVID-19 policy changes also have included extended use of PPE, such as wearing one N95 for an entire shift without removing it. Wearing masks or respirators for whole shifts increases the likelihood of injuries, such as nasal bridge ulcers, skin irritations from masks, acne, dry eyes and irritation, and headaches.
Because of COVID-19, the FDA authorized the use of foreign respirators from China and Europe. However, new products sourced by their hospitals did not meet the standard of US-approved N95s, and they were unacceptable for use. Hopkins notes that poor adherence, therefore, is no surprise, especially when healthcare workers have to rely on poor quality products that harm them when they use them.
“If you don’t have a respiratory protection program, it’s time to develop one,” says Hopkins. “If you do, reevaluate it and see where you can make some improvements.”
She says to consider the hierarchy of controls and remember that the higher up the pyramid changes can be made, the less dependence on factors like supply chain and individual actions by personnel.
Managers also can make policy and programmatic changes now, like building stockpiles of certain supplies, establishing personnel vaccination policies and programs, and looking at how to improve mask or respirator adherence at the ground level.
She says to find out preferences frontline workers have and which products aren’t working for them, and use that information to guide purchasing and policy decisions.
“Because of the pandemic,” says Hopkins, “those who don’t normally use masks and respirators have started to, and we’ve seen them doing things that undermine their effectiveness.”
Managers should provide a comprehensive program that addresses the rationale and the practical how-to of correct respiratory protection and then competency testing to ensure that personnel know how to use masks and respirators properly before they are in an exposure situation.
“In the end,” says Ofstead, “you should not rely solely on masks or respirators to keep you safe. They are like seatbelts that reduce risk, but do not prevent accidents.” ✥
Editor’s Note: This webinar was supported by an educational grant from Healthmark. All Ofstead & Associates’ webinars will be free for 2021, using the code NEWYEAR. Visit https://ofstead.elevate.commpartners.com.
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