A few things I’d like to say before I present information on masks and respirators. In my opinion every COVID-19 positive or suspected patient should be wearing a minimum of a surgical mask when a caregiver is in the room. The best place to stop an infection is at the source. In addition, I feel strongly that every patient walking into the ED should be required to wear a surgical mask for the length of their stay. With the potential length of the “incubation period” from the time of infection until presentation of symptoms, our ED staff deserve to be protected from the asymptomatic contagious patient.
Ok, back to the topic at hand. Absolutely the most important part of your PPE is oral and nasal protection as this is the most common route of infection. That’s where masks and respirators come in. There are multiple devices out there to meet this goal, providing multiple levels of protection. These devices are broken into three general categories – masks, demand respirators, and powered respirators.
Let’s start with single use and surgical masks. These masks are for protecting the wearer from debris and large droplets. As shown in the pictures they are available in multiple colors – depending on the manufacturer. These masks are also available with an attached face shield which will help to protect the eyes of the wearer. Both single use and surgical masks are rated to filter 95% of particles 3.0 microns and greater. If you recall the size of the SARS-CoV-2 virus from the last post ( 0.06 – 0.14 microns) this mask will not protect you from contracting COVID-19. Do not wear it into a known or suspected COVID-19 patient’s room!!
The next level up in protection is the demand air-purifying respirator. A demand respirator is an atmosphere-supplying respirator that admits breathing air to the wearer only when a negative pressure is created inside the device by the wearer’s inhalation. Demand respirators are available in several configurations including the dust mask or half mask, the elastomeric half mask, and the elastomeric full facemask. These masks require an annual fit test to ensure the wearer has / identifies the proper size and/or style of demand respirator which will seal properly against the their face.
There are four fit testing compounds which are approved by the Occupational Safety and Health Administration. Those compounds are Isoamyl acetate, Saccharin, Bitrex (Denatonium), and Irritant smoke. Isoamyl acetate, which smells like bananas, is used only for the testing of elastomeric masks. Saccharin, which has a sweet taste, and Bitrex, which has a bitter taste, are used for the testing of both the dust mask and elastomeric types respirators. Irritant smoke is used infrequently. To perform the fit test the wearer donns the respirator. A hood is then placed over the patients head and the testing agent is introduced into the hood. If the patient can either smell or taste the testing agent the fit test is failed.
The dust mask or half mask respirator is what most of us in healthcare are used to. This configuration includes the N95. As we know, these masks are available in different styles – some of which include an exhalation valve or a face shield. They are also available in different filtration capabilities which will be discussed later. Several of these styles are shown below. Sometimes if an individual cannot pass a fit test with one style of mask, they can try one of the other styles and obtain satisfactory results.
The elastomeric half mask respirator is not typically used in the healthcare setting, but is not inappropriate for that use. As you can see from the pictures these respirators have two filters – one on each side of the mask. These filters can be configured differently depending on the application. They always have a particulate filter similar to, but generally thicker than, the material used for a dust mask respirator. In addition, some models have filter cartridges which are mounted inside the particulate filter. These cartridge filters target specific gases such a organic vapors or acids. The organic vapor filters make cleaning up a Code Brown a much less unpleasant duty! This type of respirator is usually much easier to obtain a satisfactory seal to the wearer’s face. Another advantage of this type of respirator is the ease of inhalation compared to the mask type of respirator. Also, these types of respirators have an exhalation valve which tends to reduce fogging of glasses or goggles. These respirators also require annual fit testing. When donning these respirators they should be “cleared” to ensure a proper seal. This is accomplished by holding a hand over the exhalation valve and strongly exhaling. This will force air out of the respirator around the seal of the mask. Once that is accomplished, the wearer places a hand on each of the filtration units (which will block air coming into the respirator) and strongly inhales. This will seat the respirator seal against the wearer’s face. One final advantage to these types of respirators is, upon doffing, the entire respirator – excluding the filters – may be wiped down with non-bleach sanitizing wipes.
The elastomeric full facemask respirator is a elastomeric half mask respirator with the addition of a clear face shield which seals around the wearer’s face. This type of respirator has the same advantages as the elastomeric half mask respirator with the addition of upper face and eye protection. The filters on these respirators are configured just like those on the elastomeric half mask respirator. Annual fit testing is required for these respirators and they should also be “cleared” as part of the donning procedure. One drawback with the full facemask respirator is you are unable to wear glasses because the glasses with break the face seal on each side of the mask. Some manufacturers have an optional spectacle insert which you can take to your optometrist and have fitted with lenses. If this option is not available you will need to wear contacts with this type of mask. This respirator may also be wiped down with sanitizing wipes upon doffing. Check specific manufacturers instruction, but generally clear plastic face shields should only be wiped with alcohol to prevent clouding.
The particulate filters for the demand respirators are all rated in the same way. The rating system was developed by the National Institute for Occupational Safety and Health (NIOSH) which is a subordinate of the Centers for Disease Control. These NIOSH ratings are alphanumeric – consisting of a letter and a number. The letters include N, R, and P:
- N = Not Oil Resistant – Suitable for both healthcare and also around the house for protection from molds and dust
- R = Oil Resistant – Good for use against solid and liquid particulates that may contain oil because the filter media won’t allow the oil or fat coated particle to slip by like it could in a dry mask. These filters typically are useable for only 8 hours before they should be thrown away.
- P = Oil Proof – Similar to but better than the R rated filter. If the filter remains undamaged and breathing resistance is not detected the filter can be used indefinitely although most times a 40 hour wear limit is put on the filter.
The numbers for the air-purifying demand respirator particulate filter NIOSH ratings signify the minimum percentage of particles filtered at a size of 0.3 microns – which has been determined to be the most penetrating particle size. The numbers include:
- 95 = 95% of particulates filtered
- 99 = 99% of particulates filtered (uncommon availability)
- 100 = 99.97% of particulates filtered
These particulate filters function in some rather interesting ways. Filtration by sieving is accomplished when the filtered particle physically cannot pass through the voids in the filter media and is trapped. Inertial impaction filtering occurs when the filtered particle is moving so fast it leaves the airstream and slams into a filter fiber and is trapped. Diffusion filtration results from the randow and chaotic (Brownian) behavior of the smaller particles in the airstream which eventually results in them exiting the airsteam and either impacting a filter fiber or being electrostatically captured by it. Electrostatic binding, or interception, of particles occurs when a layer of the filter has an opposite charge to that of a nearby particle, the particle is attracted to the fiber, and becomes trapped. Because of this electrostatic effect these filters are capable of trapping particles smaller than the 0.3 micron size.
The being said, I still must ask if there is a dust mask or half mask respirator which is generally available that is more protective than an N95, specifically the N100, why isn’t that the standard basic respirator for healthcare? I don’t know about you, but I would really appreciate that extra 5% protection! Also, since the corona viruses and influenza have a lipid envelope for the outer layer of their capsid why are we not using P100 filters?
The final category of respiratory protection devices are the Powered Air Purifying Respirators or PAPRs. As the name suggests these respirators supply purified air to the user instead of requiring them to demand it. The stereotypic PAPR consists of a blower / filter / power unit which is worn on a waist belt. An air supply hose is connected from this unit to a elastomeric full facemask, partial hood, or full hood. This results in a positive pressure environment inside of the headgear. Several benefits here. If a momentary breach in the seal of the headgear occurs, the positive pressure furnishes a measure of protection against contamination. The positive pressure environment within the headgear also makes user inhalation easier and the airflow provides some cooling and reduction in fogging of glasses. There is also a PAPR version where the blower fan and filter are mounted on the front of an elastomeric full facemask and the power unit is worn on the belt.
Filters in all types of PAPRs are HEPA rated. These filters use a different rating method but equate to the protection provided by a NIOSH N100 filter in that they filter a minimum of 99.97% of particles at a size of 0.3 microns.
Another type of PAPR has been developed by Bio-Medical Devices International which they have named the MAXAIR CAPR (Controlled Air Purifying Respirator). The CAPR is similar to a traditional PAPR configuration but is much lighter in overall weight. With this system the only part of the unit which is not on the head is the power supply. This battery pack is small enough to fit in your pocket under your isolation gown. The three-speed blower looks like a computer cooling fan and is mounted in the upper back of the helmet. The HEPA filter is within the top of the helmet. I’ve worn these multiple times and found them very comfortable. There are a, however, a few drawbacks that I noted. With the blower fan running – especially if it is on high – it can be difficult to hear. Also, I have found it is difficult for patients to understand me, but this is no different than a traditional PAPR. The final issue is a biggie. When donning the CAPR DO NOT grasp it by the face shield! If you do, the face shield will eventually crack, rendering the unit unserviceable.
Another style of PAPR, which I really like, is made by an Australian company by the name of CleanSpace Technology. As shown in the 6 pictures below, these PAPRs are available in either half mask or full facemask respirators. The unique feature with these respirators is the fact the battery / blower / filter unit is suspended behind the wearers neck. This unit is only supposed to way just slightly over 1 pound. The battery / blower / filter unit is then connected to the face piece by ducts on each side of the face. Very nice design.
When I started writing this post it was mainly for informational purposes. While I was gathering the information for this I was told, and later verified, that on or about April 1 The Joint Commission issued a Statement supporting staff bringing their own masks (including home made as a last resort)@1” or respirators if adequate protection is not provided by their employer:
Also, on March 14 OSHA issued a temporary enforcement discretion policy regarding FIT testing of respirators:
In addition, on March 28 the FDA issued an Emergency Use Authorization letter in which, among other things, they allow the temporary use of certain filtering facepiece respirators (FFRs) not previously approved for use in healthcare settings:
The devices must be listed on NIOSH’s Certified Equipment List. Basically, if a respirator was approved by NIOSH for industrial or commercial use it’s temporarily approved by the FDA for use in healthcare settings.
I hope I’ve provided you with a little better understanding of the types of devices used to protect our respiratory system when caring for patients with contageous diseases. I encourage you all to keep in mind the advice of Aaron Mishler, RN which I presented in one of my earlier posts – don’t go into an isolation room without the proper PPE. Don’t do it voluntarily, don’t be bullied into it.
Until the next time, God bless! Please Share and Follow! Thanks.
Nursing In The Trenches 
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