(a)  Temperatures and Relative Humidity

(1)           The heating and air conditioning systems shall be designed to provide the temperature and humidities shown below:

Area Designation                                 Temperature                                         Relative Humidity


Operating                                              70‑75° F*  21‑24° C*                         50‑60

Recovery                                               70-75° F*  21-24° C*                         30-60


*Variable Range Required


(2)           For all other occupied or use areas, a minimum design temperature of 72°F. (22°C) at winter design conditions shall be provided.

(b)  All air‑supply and air‑exhaust systems for the operating suite and recovery area shall be mechanically operated.  All fans serving exhaust systems shall be located at the discharge end of the system.  The ventilation rates shown in this Paragraph shall be minimum acceptable rates and shall not be construed as precluding the use of higher ventilation rates.

(1)           Outdoor intakes for operating rooms shall be located not less than 30 feet (9.14 m.) from exhausts from other ventilating systems, combustion equipment and plumbing vents and at least 3 feet 0 inches (.92 m.) above the roof and 6 feet (1.83 m.) above ground level.

(2)           The ventilation systems shall be designed and balanced to provide the pressure relationship as shown in this Paragraph.

(3)           All air supplied to operating rooms shall be delivered at or near the ceiling of the area served and all exhaust from the area shall be removed near floor level. At least two exhaust outlets shall be used in all operating rooms.

(4)           The bottom of any room supply air inlets, recirculation, and exhaust air outlets shall be located not less than 3 inches (7.62 cm.) above the floor.

(5)           Corridors shall not be used to supply air to or exhaust air from any room, except that exhaust from corridors may be used to exhaust‑ventilate bathrooms, toilet rooms, janitors' closets and electrical or telephone closets opening directly on corridors.

(6)           All ventilation or air conditioning systems serving operating rooms shall have a minimum of two filter beds:

(A)          Filter bed No. 1 shall be located upstream of the air conditioning equipment and shall have a minimum efficiency of 25 percent.  Filter bed No. 2 shall be downstream of the supply fan and of recirculating spray water and water reservoir‑type humidifiers. Filter bed No. 2 shall have a minimum efficiency of 90 percent.

(B)          All filter efficiencies shall be certified by an independent testing agency and shall be based on the atmospheric dust spot efficiency determination in accordance with ASHRAE Standard 52‑68; except that the exhausts from all laboratory hoods in which infectious or radioactive materials are processed shall be equipped with filters having a 99 percent efficiency based on the DOP (dioctyophthalate) test method and there shall be equipment and procedure for the safe removal of contaminated filters.

(C)          Filter frames shall provide an airtight fit with the enclosing ductwork.  All joints between filter segments and the enclosing ductwork shall be gasketed or sealed to provide a positive seal against air leakage.  Each filter bed serving sensitive areas or central air systems shall have a manometer installed across each filter bed.

(D)          Ventilation systems serving recovery rooms shall not be tied in with soiled holding or work rooms, janitors' closets, or waiting rooms if the air is to be recirculated in any manner except through approved filters.

(7)           Air handling duct systems shall not have duct linings.

(8)           The following general air pressure relationships and ventilation shall apply:



Pressure                 Total Air                 All Air

Relationship         Changes per          Exhausted             Recirculated

Area                                       to Adjacent           Hour Supplied      Directly to             Within

Designation                           Areas                      to Room                Outdoors               Room Units


Operating Room                  P                              25                           Optional                Only with



Recovery Room                   E                             6                              Optional                See Sub-



of this


Soiled Workroom


Soiled Holding                     N                             10                           Yes                          No

Clean Workroom


Clean Holding                      P                              4                              Optional                Optional

Examination Room            +/-                           6                              Optional                Optional

Treatment Room                 +/-                           6                              Optional                Optional

Medication room                 P                              4                              Optional                Optional

X-Ray (Diagnostic

And Treatment)                   +/-                           6                              Optional                Optional

Laboratory (general)           N                             6                              Optional                Optional


P = Positive                           N = Negative      E = Equal     +/-   = continuous Directional control not required


(9)           Operating rooms or procedure rooms which are used with either life sustaining electrical equipment or identified as a critical care location shall comply with the requirements for ventilation in NFPA 99, Chapter 5, Environmental Systems.

(10)         Prior to occupancy of the facility, the facility shall obtain documentation verifying that all mechanical systems have been tested, balanced, and operated to demonstrate that the installation and performance of these systems conform to the approved design.  Test results shall be maintained in the facility maintenance files.

(11)         Upon completion of equipment installation, the facility shall acquire and maintain a complete set of manufacturers' operating, maintenance, and preventive maintenance instructions, parts lists, and procurement information including equipment numbers and descriptions. 

(12)         Operating staff shall be provided with instructions for properly operating systems and equipment.

(c)  Medical gases:  The performance, maintenance, installation, and testing of medical gas systems shall comply with the requirements of National Fire Protection Association Standard 99.  When any piping or supply of medical gases is installed, altered, or augmented, the altered zone shall be tested and certified as required by National Fire Protection Association Standard 99.  Testing shall be conducted by the facility and at least one other independent testing organization to ensure that the system is safe for patient use.


History Note:        Authority G.S. 131E‑149;

Eff. October 14, 1978;

Amended Eff. April 1, 2003; December 24, 1979.