Alaska Tuberculosis Program Manual - Epidemiology - State of Alaska

Airborne Infection Isolation
in a Healthcare Facility
In airborne infection isolation (AII), the patient is placed in an AII room, usually within a
hospital or healthcare facility. The main characteristics of an AII room (for new or
renovated buildings) are that it has negative air pressure relative to the hall and 12 or
more air exchanges per hour, of which at least two exchanges are outside air. For
existing structures, six or more air exchanges per hour are acceptable.
See Table 5 : Air changes per hour (ACH) and time required for removal
efficiencies of 99% and 99.9% of airborne contaminants* 32 for information on
estimating the time necessary to clear the air of airborne Mycobacterium complex after
the source patient leaves the area or the aerosol-producing procedures are complete.
Table 5 : Air changes per hour (ACH) and time required for removal efficiencies of
99% and 99.9% of airborne contaminants* 33
Air changes per hour (ACH) and time in minutes required for removal efficiencies of
99% and 99.9% of airborne contaminants* 34
A L A S K A T U B E R C U L O S I S P R O G R A M M A N U A L INFECTION CONTROL 17.18
Revised November 2012
ACH 99% 99.9%
2 138 207
4 69 104
6 46 69
12 23 35
15 18 28
20 14 21
50 6 8
400