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Respirators as a Precaution for Hantavirus Infection
Update on the Nomenclature and
Use of Respirators as a Precaution for Hantavirus Infection:
February, 1999
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| a) half-mask air-purifying (or
negative-pressure) respirator |
The CDC "Hantavirus
Pulmonary Syndrome--Updated Recommendations for Risk Reduction"(1)
describe precautions for persons who are involved in the cleanup
of homes of confirmed cases of hantavirus
infection or of areas with heavy rodent infestation and for workers
in affected areas who are regularly exposed to rodents. Among these
precautions is the wearing of one of the following types of respirators(2)
equipped with a high-efficiency particulate air (HEPA) filter:
Recent changes in the nomenclature and certification of the type
of filters used in these respirators include the discontinuation
of the HEPA designation and the designation of new classes of
filters. As shown on the chart below, the N-100 (99.97) is
equivalent to the previous HEPA filter.
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| b) powered air-purifying respirator (PAPR) |
Use of an N-100 filter should provide the same protection as the
HEPA filter. Due to the nature of the virus, no studies have been
able to test the efficacy of either the HEPA or N-100 filters in protecting
against HPS transmission. Available evidence suggests that HPS is
transmitted by inspiring small (less than 5 micron) viral particles
in aerosols which the N-100 is the most effective in removing.
Cautions: As described in CDC "Hantavirus
Pulmonary Syndrome--- Updated Recommendations for Risk Reduction",
all negative-pressure respirators are fit-dependent. Anything that
interferes with the respirator’s face seal, such as facial
hair, will allow ambient air to bypass the filter medium in the
respirator(3). Ideally, users should be fit-tested with the same
make, model, style, and size of respirator that will be actually
used. Respirator practices should follow a comprehensive user program
and be supervised by a knowledgeable person.
New Classes of Filters for Respiratory Protection
Devices(4)
| New classes of filters †† |
Characteristics |
| |
Equivalent to HEPA |
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| N-95 |
N-99 |
N-100 (99.97) |
Not resistant to oil |
| R-95 |
R-99 |
R-100 (99.97) |
Resistant to oil |
| P-95 |
P-99 |
P-100 (99.97) |
Oil Proof |
†† number indicates % efficiency in removing monodispersed
particles 0.3 micrometers in diameter.
Authority for testing and certifying these respirators has been given exclusively to
NIOSH. For additional information:
(1) MMWR
Recommendations and Reports, July 26, 2002; 51[RR-9]
(2) All of these respirators can be purchased from commercial suppliers of laboratory
safety equipment. The items displayed here are intended to show the general design
of the respirator and do not constitute endorsement of any particular brand of respirator.
(3) MMWR 47(40): 1045-1049, demonstrates importance of fit testing for all
negative-pressure respirators.
(4) As described in NIOSH 42, CFR 84.
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National
Center for Infectious Diseases
