Article Archive
Focus on Hazmat
SCBA, An Article on PPE
Vol. 21 No. 1

Self Contained Breathing Apparatus is not a new idea. The concept of a device that would make it possible for mankind to survive in hostile environments dates back to antiquity. No one knows for sure when it happened but at some point in time some innovative soul hit upon the idea of using a hollow reed as a means of obtaining air while being submerged in water. This principle survives to the present day and is still encountered in line-supplied diving apparatus. The hollow reed is replaced by a rubber hose and a compressor supplants lung power but the principle is there; we pump air down to a diver working under the surface of the water and he is able to survive and function effectively in an otherwise inhospitable environment.

Much has been written and more has been taught about the need for clean pure air for SCBA but relatively little attention has been paid to the "other" function of SCBA, the prevention of contact with any harmful airborne substance by the face and the interior parts of the body.

With the exception of Class A encapsulating suits all personal protective clothing leaves the face without protection. Thus protection for this vitally important area must come from elsewhere i.e. the mask or face-piece of the SCBA. This face-piece serves a double function; it is part of the respiratory circuit and it is also a mechanical barrier to prevent the entrance of air-borne particulates, mists, vapors and gasses into the lungs or onto the skin and ultimately through absorption, into the systemic circulation. It is de-facto protective clothing for the interior of the body.

Face-pieces have come a long way from the "one size fits all" molded rubber product that was common just a few years ago. Now face-pieces can be purchased in a variety of shapes and sizes to fit virtually any facial configuration. In extreme cases at least one supplier can provide a custom fit face-piece.

Because of the availability of better fitting face-pieces with their superior sealing capabilities, many Fire Departments and other response organizations now issue an individual face-piece to each responder. This face-piece stays with the responder whenever he exchanges the SCBA at the end of a shift or after a response in the course of which it was used.

The practice of utilizing individual face-pieces is a great help in assuring that the face-piece actually seals off the "vital triangle" of the face. Once an individual is fit-tested, adjustments made to the face piece can remain in place and need not be reset each time the mask is worn by a different user.
Materials also have undergone evolution. Now face pieces can be made in a variety of materials designed to withstand specific hazardous materials. These include butyl rubber, neoprene, and vinyl. Again custom designs are available for unusual exposures.

Of course one cannot know exactly what hazardous material will be present at any particular response. Consequently many, if not most, response organizations must rely on the standard rubber face-piece seal. However there are those organizations that respond to incidents involving specific chemicals. These would include chlorine, benzene, carbon disulfide and numerous others. These groups have the luxury of knowing in advance at least some of the chemicals that will be involved in an incident to which they are likely to respond. This makes it possible for them to be equipped with SCBA fitted with elastomer parts that will withstand that particular chemical.
Another factor involving the face-piece that should be given more attention is the seal between the wearer's face and the face-piece itself. The integrity of this mask to face seal can easily be validated by a fit test. Fit testing should be done on a periodic basis and whenever any substantial changes to the facial contour (such as injury, extensive dental work or cosmetic surgery) occur.

Fit -testing, like many other procedures has undergone refinement over the years but a very simple home-made apparatus can be very effective in the hands of a diligent operator and a cooperative subject.

All that is required is a light plywood disk fitted with a plastic curtain that extends well below the waist of the test subject. This works most conveniently when suspended so that the curtain is above head level and can be lowered during the testing procedure to enclose the test subject. A small piece of paper towel is soaked in a solution of ethyl acetate in water and fastened to a paperclip on the underside of the plywood disk. The subject is asked to execute a number of maneuvers such as turning the head to the right and left as well as up and down then bending at the waist and so on. If the seal of the face-piece is good the subject will report no detectable odor of ethyl acetate (a smell reminiscent of bananas). If he reports smelling bananas then the air mask needs to be adjusted. In cases where a subject is suspected of being less than honest an irritating smoke can be substituted for the ethyl acetate. If the subject starts coughing the seal was not complete. Other substances such as a solution of syrup of ipecac sprayed into the heat chamber can be used but the results of a failed seal are somewhat unpleasant.

One of the problems encountered in using SCBA safely is facial hair. Strangely enough a heavy "five-o-clock shadow" will make it more difficult to obtain a good face seal than a two or three day growth of beard. Each responder wearing SCBA should be clean-shaven. Some responders have been known to shave in the rear-view mirror of their response vehicle prior to donning SCBA. If the rescue phase of the incident has passed then the extra time this takes will be of little consequence and is pretty cheap insurance.

Some employees will object, for various reasons, to being asked to remove facial hair prior to donning SCBA. There should be no question about this. All facial hair MUST be removed as per OSHA as well as per common sense. There is a gray area concerning mustaches which are entirely enclosed by the mask and do not encroach on the area involved in the face to mask seal and this will have to be decided on a case by case basis. A small "tooth brush" mustache is one thing a six-inch handlebar is quite another.

In any case the policy must be enforced; if the employee will not remove the facial hair then the employee must be removed from any position wherein he could be required to utilize SCBA. There is no beard or mustache, no matter how "macho" that is worth risking death or injury to preserve.

Finally, face-pieces like any other piece of equipment, have a certain life expectancy and at the end of this period they should be replaced. Meanwhile proper maintenance will go a long way to ensuring that these items perform as expected all the time, every time.

Skin oils are deleterious to rubber and other elastomers therefore they should be removed by careful washing with soap and water from face-pieces after each use. Other decontamination procedures may be required to remove residues from the outside of the mask before washing. During the washing operation the mask should be thoroughly inspected for cracks, cuts, or chemical damage and if these are found the mask should be replaced.

Finally the mask should be rinsed in a solution of bleach and then plain water and allowed to air dry. A spray of antibacterial deodorizer completes the process and the mask is ready to be returned to service. It is important that, in those organizations in which employees are issued individual masks and are individually responsible for their care, there is no slacking in the post response decontamination protocol.

The face-piece is all that stands between the interior of the body and the toxic atmosphere. It must let clean air in and keep toxic and/or corrosive substances out. In effect it is both an airway and a protective garment for the interior of the body. Use it properly, treat it gently and care for it as if your life depended on it. That very well may be on the next run.

 
 

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