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October 25, 2001
NIOSH/CDC Interim Recommendations for the Selection and Use of Protective
Clothing
and Respirators Against Biological Agents
The approach to any potentially hazardous atmosphere, including biological
hazards,
must be made with a plan that includes an assessment of hazard and exposure
potential,
respiratory protection needs, entry conditions, exit routes, and decontamination
strategies.
Any plan involving a biological hazard should be based on relevant infectious
disease or
biological safety recommendations by the Centers for Disease Control and
Prevention
(CDC) and other expert bodies including emergency first responders, law
enforcement,
and public health officials. The need for decontamination and for treatment of
all first
responders with antibiotics or other medications should be decided in
consultation with
local public health authorities.
This INTERIM STATEMENT is based on current understanding of the potential
threats
and existing recommendations issued for biological aerosols. CDC makes this
judgment
because:
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1. Biological weapons may expose people to bacteria,
viruses, or toxins as fine
airborne particles. Biological agents are infectious through one or more of
the
following mechanisms of exposure, depending upon the particular type of
agent:
inhalation, with infection through respiratory mucosa or lung tissues;
ingestion;
contact with the mucous membranes of the eyes, or nasal tissues; or
penetration of
the skin through open cuts (even very small cuts and abrasions of which
employees might be unaware). Organic airborne particles share the same
physical
characteristics in air or on surfaces as inorganic particles from hazardous
dusts.
This has been demonstrated in military research on biological weapons and in
civilian research to control the spread of infection in hospitals.
2. Because biological weapons are particles, they will not penetrate the
materials of
properly assembled and fitted respirators or protective clothing.
3. Existing recommendations for protecting workers from biological hazards
require
the use of half-mask or full facepiece air-purifying respirators with
particulate
filter efficiencies ranging from N95 (for hazards such as pulmonary
tuberculosis)
to P100 (for hazards such as hantavirus) as a minimum level of protection.
4. Some devices used for intentional biological terrorism may have the
capacity to
disseminate large quantities of biological materials in aerosols.
5. Emergency first responders typically use self-contained breathing
apparatus
(SCBA) respirators with a full facepiece operated in the most protective,
positive
pressure (pressure demand) mode during emergency responses. This type of
SCBA provides the highest level of protection against airborne hazards when
properly fitted to the user’s face and properly used. National Institute for
Occupational Safety and Health (NIOSH) respirator policies state that,
underഊ2
those conditions, SCBA reduces the user’s exposure to the hazard by a factor
of at
least 10,000. This reduction is true whether the hazard is from airborne
particles,
a chemical vapor, or a gas. SCBA respirators are used when hazards and
airborne
concentrations are either unknown or expected to be high. Respirators
providing
lower levels of protection are generally allowed once conditions are
understood
and exposures are determined to be at lower levels. |
Interim Recommendations for the selection and use of protective clothing and
respirators against biological agents.
When using respiratory protection, the type of respirator is selected on the
basis of the
hazard and its airborne concentration. For a biological agent, the air
concentration of
infectious particles will depend upon the method used to release the agent.
Current data
suggest that the self-contained breathing apparatus (SCBA) which first
responders
currently use for entry into potentially hazardous atmospheres will provide
responders
with respiratory protection against biological exposures associated with a
suspected act of
biological terrorism.
Protective clothing, including gloves and booties, also may be required for the
response
to a suspected act of biological terrorism. Protective clothing may be needed to
prevent
skin exposures and/or contamination of other clothing. The type of protective
clothing
needed will depend upon the type of agent, concentration, and route of exposure.
The interim recommendations for personal protective equipment, including
respiratory
protection and protective clothing, are based upon the anticipated level of
exposure risk
associated with different response situations, as follows:
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1. Responders should use a NIOSH-approved, pressure-demand
SCBA in
conjunction with a Level A protective suit in responding to a suspected
biological
incident where any of the following information is unknown or the event is
uncontrolled:
−the type(s) of airborne agent(s);
−the dissemination method;
−if dissemination via an aerosol-generating device is still occurring or it
has
stopped but there is no information on the duration of dissemination, or
what the exposure concentration might be.
2. Responders may use a Level B protective suit with an exposed or enclosed
NIOSH- approved pressure-demand SCBA if the situation can be defined in
which:
−the suspected biological aerosol is no longer being generated;
−other conditions may present a splash hazard.
3. Responders may use a full facepiece respirator with a P100 filter or
powered air-purifying
respirator (PAPR) with high efficiency particulate air (HEPA) filters
when it can be determined that:−an aerosol-generating device was not used to
create high airborne
concentration,
−dissemination was by a letter or package that can be easily bagged.
These type of respirators reduce the user’s exposure by a factor of 50 if
the user
has been properly fit tested. |
Care should be taken when bagging letters and packages to minimize creating a
puff of
air that could spread pathogens. It is best to avoid large bags and to work very
slowly
and carefully when placing objects in bags. Disposable hooded coveralls, gloves,
and
foot coverings also should be used. NIOSH recommends against wearing standard
firefighter turnout gear into potentially contaminated areas when responding to
reports
involving biological agents.
Decontamination of protective equipment and clothing is an important precaution
to
make sure that any particles that might have settled on the outside of
protective
equipment are removed before taking off gear. Decontamination sequences
currently
used for hazardous material emergencies should be used as appropriate for the
level of
protection employed. Equipment can be decontaminated using soap and water, and
0.5%
hypochlorite solution (one part household bleach to 10 parts water) can be used
as
appropriate or if gear had any visible contamination. Note that bleach may
damage some
types of firefighter turnout gear (one reason why it should not be used for
biological
agent response actions). After taking off gear, response workers should shower
using
copious quantities of soap and water.
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