Personal Protective Equipment (Benefits & Limitations)
It is widely recognized that the risk of exposure should be addressed through administrative, and engineering controls, work practices and training. It is equally recognized that these controls may not prove to be adequate in situations where the risk could not be completely minimized, or in the event of an unplanned exposure. Thus the use of personal protective equipment (PPE) becomes last line of defense against exposure.
The benefits gained by wearing PPE are:
- possible prevention of exposure,
- potentially minimizing the risk should an exposure occur, and
- compliments existing controls to enhance personal protection.
It is also important to recognized the limitations associated with PPE:
- PPE only protects the individual wearing it, not anyone else in the workplace,
- discrepancy between theoretical and actual levels of protection provided exists (the latter is difficult to assess),
- PPE is only effective if correctly selected, fitted, used, and cared for, and the individual is trained, and
- the choice of PPE may compromise mobility, visibility, communication etc..
When considering the appropriate type of PPE, it is important to identify
and assess all the types of risk one will be exposed to, what risks can
be mitigated through other control mechanism, and any detrimental impact
associated with the selection of the PPE. To help in understanding and
selecting PPE, the University of Ottawa has prepared a Personal
Protective Equipment Standard.
In general vinyl, nitrile or latex* gloves are used when working with biological agents; with the choice being based on objective and subjective criteria. Some of the issues that must be considered in selecting gloves are:
- effectiveness of the barrier to biopenetration, hydration, and chemicals
- tensile characteristics, length of cuff
- quality control and assurance ( porous matrix, microscope tears, variation in density and thickness)
- personal comfort
Gloves should be changed frequently, as the integrity of the glove may be compromised by:
- hydration( long exposure to liquids)
- physical demands (stretching during donning and use)
- chemical degradation (disinfectants, solvents, drugs)
- environmental degradation (humidity, heat, cold, ultraviolet or fluorescent light)
Double gloving may help address the potential weakness associated with the above mentioned conditions.
* Latex Allergy: is a serious condition for those suffering from this allergy, and care and consideration must be offered to them by their colleagues.
The choice of lab coats must allow for complete coverage (knee length and long sleeves), snap closing and resistant to permeation of biological material and chemicals. As the wrist opening of the lab coat has not been restricted, care must be taken to prevent exposing the skin; this may be achieved by tucking the sleeve into the glove. Dangling sleeves may also result in cross- contamination as result of the edge of the sleeve dragging over multiple surfaces.
Alternatively back closing gowns with knitted cuffs may be used; the use of these are generally restricted to operations involving agents requiring higher containment (level3). Although providing greater coverage, they are more difficult to remove during an emergency.
Cleaning Lab Coats / Gowns
If disposal coats and gowns are not used, periodic cleaning is required. Basic cleaning procedures will require the appropriate bagging of the lab coat to the facility, then the use of a bleach and laundry soap using a dedicated wash cycle. Should the lab coat be known to be contaminated or after operations engaging a high risk of aerosol generation (spill), the coat/gown should first be autoclaved. All coats and gowns used in a level 3 facility must be autoclaved prior to use.
Eye protection may be addressed by standard laboratory glasses, googles or face shield depending upon the operation and risk being addressed. The main hazards to be addressed are: splashes (due to spills, or aerosols/droplet generation), impact (powders, dust, shattered objects), and radiation such as ultraviolet light, x-rays etc. Not only must the selection address the specific risk but the eye wear must be comfortable, provide good visibility and be appropriate stored and cared for.
As will all PPE selection the risk being addressed must be appropriately identified prior to selecting the respirator which will minimize the risk. Perhaps more than any other piece of equipment, respirators will only work it they are appropriately fitted and maintained. For this reason, contact ORM should you feel a respirator is required.
Surgical masks are not respiratory protection devices. They are designed to act as a means of preventing the spread of infection from the user to those around the wearer. This is achieved by filtering exhaled droplets from the wear, the fear being that these droplets may contain infectious microorganism. Their ability to prevent transmission of aerosols is highly variable.