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Introduction
Respirator is a device which is designed to protect
the wearer from inhalation of harmful contaminants. Respirators are widely used
in industry to protect workers against harmful atmospheres, and in the military
to protect personnel against chemical, biological, or radioactive warfare
agents.
There are two general classes of respirator i.e. air-purifying respirator
and air-supplied
respirator or atmosphere-supplying respirator. These two classes are classified
by the amount of face coverage it provides and the techniques it employed to
reduce or eliminate noxious airborne contents.
Air-purifying respirator
This respirator filter contaminated air through a filtering element. There
are many different types of air-purifying respirators include single use,
reusable half-facepiece or full-facepiece with replaceable filters and/or
cartridges and powered air-purifying respirator (PAPR) which have a fan to
assist in moving the air through the filtration medium. Specific filters and/or
cartridges and canisters are used for different contaminants and contaminant
combinations.
Air-supplied
respirator or Atmosphere-supplying respirator
An alternate supplying fresh air. The air for air-supplied
respirators may come from bottled air or from special air compressors that
filter the ambient air. Breathing air may be carried in tanks on a user's back,
as in the self-contained breathing apparatus (SCBA) used by firefighters or
supplied through air-lines attached to the facepiece. Most air-supplied
respirators operate in the positive pressure mode, where air flows continuously
to maintain a positive pressure inside the facepiece, reducing the potential for
inward leaks of contaminated air.
Selecting a Respirator
Respirator selection requires correctly matching
the respirator with the hazard, the degree of hazard, and the user. If an
inappropriate respirator is selected, a worker may have a false sense of
security and her/his health may be at risk.
The following
points must be taken into account:
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Identifying the nature
of the hazard, concentrations of contaminants, and the physical and chemical
properties of the air contaminant
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Nature of the work operation or process.
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Relevant permissible exposure limit or other
occupational exposure limit;
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Work activities and physical/psychological stress;
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Length of time the respirator is worn;
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Fit testing; and
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Physical characteristics, functional capabilities,
and limitations of respirators.
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