I've been told that a negative pressure room helps
to control TB bacteria. What constitutes a negative
A: A room
is said to be under negative pressure when more air is
exhausted from the room than is being supplied to it.
How does this help to control TB contaminants?
of air flow is determined by the differences in air pressure
between adjacent areas, with air flowing from high pressure
areas to lower pressure areas. If a TB patient's room
is under lower (or negative) pressure to adjoining areas,
the contaminated air should not be able to flow to the
uncontaminated adjoining areas.
Is it easy to maintain negative pressure in a room?
air flow and pressure differentials between areas of
a health care facility are difficult to control because
of open doors, movement of patients and staff, temperature,
and the effect of vertical openings. Air pressure differentials
can best be maintained in completely closed rooms. An
open door between two areas may reduce any existing pressure
differential and could reduce or eliminate the desired
Does a room under negative pressure protect these
providing care within the contaminated room?
A: This depends
on the volume of air being exhausted from the room and
the frequency at which it is removed. The only protection
provided to those within the room is contaminant removal
Is there any way to increase the protection of those
within the contaminated negative pressure rooms?
A: An air
purifier providing supplemental contaminant removal and
air changes could be employed. UV lamps may also provide
some additional protection.
How many air changes are recommended for negative
pressure rooms being used for TB patients?
A: The CDC
recommends that there be at least six total air changes
per hour, and at least two outside air changes per hour
within room air distribution to dilute or remove TB bacillus
from locations where health care facility personnel or
visitors are likely to be exposed.
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