The Mask


The protection mask was mentioned many times in the previous text. It is time for a closer look at this critical element of PPE as far as infection exposure prevention is concerned.

 OSHA’s Standard requires protection from exposure for eyes, the mucous membranes of the face and the upper respiratory tract. Depending on the degree and type of anticipated exposure, the protection for the face would consist of a surgical mask in conjunction with goggles or eye glasses with solid side shields or, alternatively, a chin-length face shield.

 Health care practice uses different kinds of masks which are often defined interchangeably. This confusion of terminology is not helpful in making an informed choice of a protection mask. Three terms are in common use: surgical mask, protective mask, and respirators.

A regular surgical mask has two layers (the external is thin and water permeable; the internal to the face is thick and water resistant).   It is obvious that the surgical mask is designed to protect the operative wound from potential infection that stems from the worker. In other words, the aim is to prevent the wearer from infecting others. Thus, if the wearer sneezes, coughs, drools, spits or talks excitedly, his or her infected fluids will be trapped in the mask and will not infect others. It used now by dental hygienists and even by tellers in banks for mutual protection.

In surgical pathology we have a specific goal due to different working conditions. The regular surgical mask’s size and composition is not sufficient. A fountain-like splash can occur in surgery, but surgery pathology handles specimens which present only rare occasions (e. g. placenta, big cysts) of splashes.

The respirators, or N95 masks, are in two grades: for industrial use and a fluid resistant mask for use in hospitals and clinical settings. The nomenclature N95 comes from the fact that these masks are supposed to filter at least 95% of all particulates that are 3 microns or larger. The N95 mask was recommended by the Centre for Disease Control & Prevention (CDC) and World Health Organization (WHO) as the respiratory protection for the bird flu virus. This mask requires individual fit-testing to be functional according their design and purpose. Reasonable in theory, the N95 mask is cumbersome, uncomfortable, and therefore unpractical for regular surgical pathology laboratory work.

The third type of protection masks are different variants of shield masks. The most popular is the Kimberly-Clark TECNOL FLUIDSHIELD mask. It has five layers. Both the internal and external (orange stripes) layers are water permeable. The three layers between them have different degrees of water resistance. Although the company advertises them as LONCET breathable film, these layers, in my experience, make the mask uncomfortable for prolonged use because the area between the mask and the face is overheated and oversaturated with exhaled carbon dioxide that decreases the percentage of oxygen in the inhaled air.


As already mentioned, the frozen section laboratory has the highest level of potential infectious exposure in the surgical pathology laboratory. Aerosols created in cryostats are places where infection could occur for the worker as well for other people in the room. The specimen in fresh state is processed at a justifiably quick pace. Multiple micron size fragments are generated in aerosol form in the cryostat by the nature of trimming/cutting.

The cryostat chamber accumulates potentially dangerous infectious materials. Hopefully, the time has gone when cryostats were full of remnants of trimmed and cut tissues of previous frozen sections cases. Cleaning the cryostat’s chamber is everyday routine in most laboratories as a matter of common sense.  The cryostat’s defrost cycle continues the cleaning job.

CLSI guidelines unequivocally state that “an N-95 particulate respirator should be worn during frozen sectioning.” However, this is an unrealistic recommendation for many reasons (difficult to breathe, individual fit-testing, necessity of permanent communication) although for some particular cases such an option should be on hand. Even a Kimberly-Clark FLUIDSHIELD mask is superfluous, except for initial sections of a cystic formation or other possible splash specimen. A regular surgical mask with ear loops is obligatory and should be enforced on technicians and pathologists without any exception.

In the case of potential exposure to tuberculosis, AIDS, SARS – coronavirus, Methicillin-resistant Staphylococcus aureus, etc., a different kind of protective mask should be used. The Kimberly-Clark FLUIDSHIELD mask is definitely advisable,


by wearing it in the upsidedown mode (Figures 15-6 and 15-7).

Figures 15-6 and 15-7. Upsidedown Kimberly-Clark FLUIDSHIELD mask.


First, two internal layers are made from unwettable material. Designed to prevent penetration of splashes, the mask is not suitable for a prolonged use. The breathing area is overheated because the mask hampers evaporation. There is also over saturation with exhaled carbon dioxide that decreases the percentage of oxygen in the inhaled air. If we add undesirable reflections of the plastic shield (WrapAround SPLASHGUARD Visor), the conditions of using the mask become more unfavorable. It is more reasonable to wear the Kimberly-Clark mask with the plastic shield upside-down. In this situation, the area of air circulation is larger.

Second, while using the “modified” Kimberly-Clark mask with the shield down, I noticed that many droplets of blood, stain, and other fluid could be found on the plastic shield. It means that the chin and the neck, as more vulnerable to contamination than the forehead, are more protected from splashes and spatters. The shield reaches the ubiquitous blue protective gown like Convertors  (ALLEGIANCE’s Impervious Gown w/Thumbhooks, Universal). One lower fold of the mask can be loosened to make the mask longer or the plastic shield can be cut to make it shorter if it is necessary for the individual adjustment. The lower strings can be tightened or loosened depending on the type of the processed specimen.  The use of protective glasses with solid side shields at the grossing table is a necessity and the OSHA’s requirement without any exception.

If an air permeable light fabric extension to both sides of the mask were added with strings tight behind the neck, this design would make the mask more protective and comfortable for a prolonged work. (Figure 15-8) This “improvement” would not substantially increase the cost of the mask. Perhaps, some vendors will come across these pages of the book.

Perhaps, some other vendors will come across this post and implement this principle of a protective mask design. Only a simple design is workable.


Additional remarks. The mask is intended for use in a very hazardous environment. People work in potentially contaminated gloves. Sometimes the gloves are not changed before taking a mask out from the box soiling other masks.

1. The packing of the Kimberly- Clark TECNOL FLUIDSHIELD masks in the box should be loose (less than 25). 2. The packing box should be redesigned.3. The mask should be distributed for pathology laboratories in individual wrapping.   

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