Application Note

2 Fluke Corporation Airborne particle counters provide vital information for maintaining indoor air quality in healthcare facilities
The spread of infection through the indoor air is a serious
potential problem in healthcare facilities. Such infections
can stem from two sources:
• Infectious agents produced by people inside the facility,
such as Tuberculosis, Rubella (measles) and influenza
• Agents normally present in the human environment that
can endanger patients who have compromised
immune systems. Such organisms include
Aspergillus
fumigatus
, a common species of mold, and others.
Other airb
orne particulates, such
as inorganic materials and aller
-
gens, while capable of causing
health problems, pose a lesser
threat to patients. These contami-
nants will not be addressed in
this document, though the air fil-
tration and air pressure balancing
techniques that help control bio-
logical pathogens can also control
odors, dust and other non-viable
air pollutants.
To control the movement and
spread of infectious agents, facil-
ity designers and managers
establish special purpose spaces
called Airborne Infection Isolation
(AII) or patient isolation room,
and Protective Environment (PE)
facilities. In both of these special
ventilation spaces, air pressures
are reg
ulated to move air from
clean to dirty areas.
The AII room would house a
patient judged to b
e a sourc
e of
airb
or
ne infection, such as
Mycobacterium tuberculosis or
measles v
irus
. V
ents draw air
from the room and exhaust it out
-
side the building. High efficiency
particulate air (H
E
P
A) filters ma
y
b
e used to help remove particles
from the air
. Makeup air flowing
into the room is balanced so that
the room remains under negative
air pressure. Thus the direction of
airflow under the door or when
the door is opened is
into the
space, rather than out, helping
contain infectious particles.
The Protective Environment
facility is designed to keep infec-
tious agents out and protect
immuno-suppressed patients and
others, such as bone-marrow and
organ-transplant patients and
premature infants, who are espe-
cially vulnerable to opportunistic
infectious agents. The CDC
ii
rec-
ommends that PE facilities be
maintained under positive air
pressure, with directional airflow
(from one side of the room, across
the patient to the exhaust) and
twelve or more air changes per
hour
. Clean air is supplied
through H
E
PA filters, and point-
of-use HEPA filters may also be
used
. Air flow
ing through an
open door or leak moves out of
the space, not in.
Sources of IAQ Problems in Healthcare Facilities