Basic Documentation

Siemens Industry, Inc. Page 9 of 12
Document No. 149-903

Supply air intakes should not face or be in close
proximity to helicopter landing/takeoff sites,
since the high air turbulence of flight operations
could drive considerable dust, debris, and fumes
into a supply air intake.
 All ventilation system ductwork should be
equipped with access doors to allow inspection,
service, and cleaning. Access panels should
also be provided at all duct components, such
as heating and cooling coils, dampers, turning
vanes, air terminals, etc.
Exhaust Air–Care must be exercised in the system
design and particularly in the location of the exhaust
air inlets. The following list contains important design
criteria for healthcare exhaust air systems:
 Infection isolation room exhaust ductwork must
be labeled as Contaminated Air at 10-foot
intervals within the facility and on the discharge
housing in compliance with CDC Guidelines.
Exhaust air ducts should also be provided with
access panels to enable inspecting, cleaning,
and servicing components.
 Exhaust air discharge outlets should be as high
as practical and, therefore, most typically on the
building roof.
 All potentially infectious exhaust should be
discharged by means of a vertical stack or
vertical fan discharge arrangement so that the
exhaust air is released as high as possible.
Mushroom type rooftop exhaust fans are not
suitable for potentially infectious exhaust.
 The exhaust air discharge outlet must not have
a rain cap or other elements that could disrupt
the upward direction of the exhaust air stream.
Room Design Considerations
The following additional design considerations are
recommended for implementation in new facilities
and, where possible, in facilities undergoing
extensive renovation:
 Appropriate permanent signs must clearly
indicate the special nature of the rooms
(infectious or protective isolation), as well as
clearly indicate the type of protective clothing
(gowns, masks, gloves, etc.) that must be worn
and procedures to be followed. A changing
room, with ample storage for protective items,
should be available for those entering the
isolation room area.
 Airborne infection isolation room perimeter walls,
ceiling, and floors, including penetrations must
be sealed tightly so that air does not infiltrate the
room environment.
16
 Isolation room and anteroom doors are required
to have self-closing devices on all room exit
doors
17
.
 Protective environment room walls should be
smooth and impervious to the disinfectant
solutions normally used to sanitize the room.
Solid ceilings (such as drywall) are also required
in these rooms. Ceiling height should be
minimized (8 feet) to maximize the ventilation
(ACH) rate effectiveness and to provide
adequate space above the ceiling for ventilation
system ductwork. No carpeting should be in the
patient rooms or hallways, and furniture outer
covering should be impervious to liquids.
 Humidity in isolation rooms should not exceed
60% rh, since higher values promote fungal
growth. When additional moisture is required to
maintain the desired humidity level, it is best to
add the supply air via a steam type humidifier
and potable water for steam generation (not
chemically treated boiler water).
 All ventilation systems serving isolation rooms
should be on the facility essential electrical
power supply system.
Ultraviolet Germicidal Irradiation
In some climates or in certain high-risk areas of a
facility, proper airborne infection isolation room
ventilation may be supplemented by the application
of Ultraviolet Germicidal Irradiation (UVGI). This may
be particularly applicable for larger isolation rooms
(wards), waiting rooms, or long-term patient common
areas such as recreation rooms. Studies have
shown that TB and other infectious organisms are
killed when sufficiently exposed to UVGI. However, a
major concern about UVGI is ensuring against
personnel exposure and its continued effectiveness.
UVGI systems must, therefore, be properly installed
and maintained.
UVGI may be applied in several forms:
 In TB sputum collection booths, bare UV bulbs
can be used to irradiate the entire booth when it
is not occupied.
 UVGI bulbs in pre-configured units may also be
incorporated to prevent the growth of microbes
on HVAC system components, such as cooling
coils and filter surfaces. Since the UVGI
disinfecting process requires a finite exposure
16. AIA Guidelines 2006, section 3.2.2.4 p.43
17. Ibid.