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[OSHPD 1, 1R, 2, 3, 4 & 5]
407.1 General
407.1.1
All supply-air, return air, and exhaust-air systems shall be mechanically operated and such systems for areas listed in Table 4-A shall be operated continuously. Natural ventilation through windows or other openings such as louvers will be considered as supplemental to the required mechanical ventilation systems.

Exceptions:
  1. Natural ventilation shall not be used in airborne infection isolation rooms and protective environment rooms.
  2. The number of air changes may be reduced to 25 percent of the indicated value in Table 4-A, when the room is unoccupied, if provisions are made to ensure the following:
    1. The number of air changes per hour indicated is reestablished whenever the space is occupied.
    2. The pressure relationship with the surrounding rooms is maintained when the air changes per hour are reduced. In areas requiring no continuous directional control as identified in accordance with Table 4-A, ventilation systems may be shut down when the space is unoccupied and ventilation is not otherwise required. Ventilation shall not be reduced in rooms specifically used for airborne infection control, such as waiting rooms, triage rooms, corridors, reception areas, areas adjacent to waiting areas, airborne infection isolation rooms, negative pressure exam room, negative pressure x-ray treatment rooms, and protective environment rooms. All operating and delivery rooms shall maintain a minimum of six air changes per hour of total air when not in use.
407.1.2
Fans serving exhaust systems shall be located at the discharge end of the system. The ventilation rates shown in Table 4-A shall be considered as minimum acceptable rates and shall not be construed as precluding the use of higher ventilation rates if they are required to meet design conditions.
407.1.3 Services/Systems and Utilities
(Refer to Section 1224.4.1 of the California Building Code).
407.2 Outdoor Air Intakes and Exhaust Outlets
407.2.1 Outdoor Air Intakes
Outdoor air intakes shall be located at least 25 feet (7.62 m) from exhaust outlets of ventilating systems, combustion equipment stacks, medical-surgical vacuum systems, cooling towers, and areas that may collect vehicular exhaust or other noxious fumes. Plumbing vents shall be located in relation to outdoor air intakes per California Plumbing Code. The bottom of outdoor air intakes shall be located as high as practicable, but not less than 10 feet (3048 mm) above ground level. If installed above the roof, they shall be located 18 inches (457 mm) above roof level or 3 feet (914 mm) above a flat roof where heavy snowfall is anticipated.

Exceptions:
  1. These dimensions may be reduced if it is demonstrated by the submission of details and calculations that location of intakes with respect to exhausts and their orientation, or the use of special filters, provides equal performance.
  2. The requirements regarding the bottom of outdoor air intakes and installation through the roof do not apply to skilled nursing facilities, intermediate-care facilities or nonsensitive areas in correctional treatment centers.
407.2.2 Exhaust Outlets
Exhaust outlets shall be located a minimum of 10 feet (3048 mm) above adjoining grade and 10 feet (3048 mm) from doors, occupied areas, and operable windows.

Exception: Airborne infection isolation rooms shall comply with Section 414.1.
407.3 Air Balance
407.3.1
The ventilation systems shall be designed and balanced to provide the general air balance relationship to adjacent areas, shown in Table 4-A. The ventilation systems shall be balanced in accordance with the latest edition of standards published by the Associated Air Balance Council (AABC), the National Environmental Balancing Bureau (NEBB), or the Testing, Adjusting and Balancing Bureau (TABB).
407.4 Air Circulation
407.4.1
Design of the ventilation system shall provide air movement that is generally from clean to less clean areas.
407.4.1.1
Air supplied to operating rooms, cesarean operating rooms, cardiac catheterization labs, cystoscopy rooms, delivery rooms, and nurseries shall be delivered at or near the ceiling of the area served. In these areas and in morgues and autopsy rooms all air removed from the area shall be removed near floor level. Exhaust or recirculation inlets shall be located not less than 3 inches (76 mm) nor more than 8 inches (203 mm) above the finished floor, except in morgues and autopsy rooms where all of the exhaust air is removed through an autopsy table designed for this purpose. At least two exhaust or recirculation air inlets of equal capacity shall be used in all cardiac catheterization labs, cystoscopy rooms, operating rooms, and delivery rooms and shall be located not less than 3 inches (76 mm) nor more than 8 inches (203 mm) above the finished floor.

Exception: For airborne infection isolation rooms and protective environment rooms, see Sections 414.0 and 415.0.
407.4.1.2
Room supply air outlets and room recirculation and exhaust air inlets installed in nonsensitive areas shall be located not less than 3 inches (76 mm) above the floor.

Exception: For airborne infection isolation rooms and protective environment rooms, see Sections 414.0 and 415.0.
407.4.1.3
Corridors shall not be used to convey supply, return, transfer or exhaust air to or from any room if the corridor is required to be fire resistive construction per the California Building Code.

Exceptions:
  1. Mechanically exhausted toilet rooms of 50 square feet (4.7 m2) or less and small rooms of 30 square feet (2.79 m2) or less such as janitor closets, housekeeping rooms, and electrical or telephone closets opening directly onto corridor.
  2. Air transfer caused by pressure differentials in rooms required to have a positive or negative air balance by Table 4-A.
407.4.1.4
No space above a ceiling may be utilized as an outside-air, relief-air, supply-air, exhaust-air, or return-air plenum.

Exception: Designs specifically approved by the enforcing agency.
407.4.1.5
Air from a patient room, exam room, treatment room shall not be transferred to another similar room without first having passed through air filters as required by Table 4-B or Table 4-C.

TABLE 4-B
FILTER EFFICIENCIES FOR CENTRAL VENTILATION AND AIR-CONDITIONING SYSTEMS IN GENERAL ACUTE CARE HOSPITALS, ACUTE PSYCHIATRIC HOSPITALS, OUTPATIENT FACILITIES, AND LICENSED CLINICS1
AREA DESIGNATION
MINIMUM NUMBER OF FILTER BANKS FILTER EFFICIENCY % FILTER BANK
(MINIMUM EFFICIENCY REPORTING VALUE MERV)5
NO. 11
NO. 21
NO. 31
Orthopedic operating room, bone marrow transplant operating room, organ transplant operating room, NICU formula preparation room, NICU treatment area/room
3
30%
90%
99.97%3
(8)
(14)
(17)
Protective environment rooms
3
30%
90%
99.97%4
(8)
(14)
(17)
Angiography; cardiac catheterization labs; operating
rooms; interventional imaging procedure
rooms; delivery rooms nurseries; patient care, treatment, cystoscopy, cesarean operating room, diagnostic,
and related areas; airborne infection
isolation rooms; areas providing direct patient service or clean supplies such as sterile and clean
processes, and patient area corridors
2
30%
90%
(8)
(14)
Laboratories
2
30%
80%
(8)
(13)
Administrative, med staff support areas, bulk storage,
soiled holding areas, food preparation areas, public cafeterias, and laundries
1
30%
(8)
Psychiatric hospitals intended for the care and
treatment of inpatients who do not require acute medical services
1
30%
(8)
  1. 1 Based on ASHRAE 52.2.
  2. 2 Based on DOP test in accordance with MIL-STD-282 or based on ASHRAE 52.2.
  3. 3 HEPA filters at air outlet or other locations when approved by the Authority Having Jurisdiction.
  4. 4 HEPA filter located in the supply duct which serves the positive-pressure isolation room or rooms may serve more than one supply outlet and more than one positive-pressure isolation room. HEPA filter or a filter with minimum efficiency reporting value (MERV) of 17 installation shall be designed and equipped to permit safe removal, disposal and replacement of filters.
  5. 5 The numbers in parentheses represent MERV rating based on ASHRAE 52.2.
TABLE 4-C
FILTER EFFICIENCIES FOR CENTRAL VENTILATION AND AIR-CONDITIONING SYSTEMS IN SKILLED NURSING FACILITIES AND INTERMEDIATE CARE FACILITIES AND CORRECTIONAL TREATMENT CENTERS1
AREA DESIGNATION
MINIMUM NUMBER OF FILTER BANKS FILTER EFFICIENCY % FILTER BANK
(MINIMUM EFFICIENCY REPORTING VALUE MERV)3
NO. 11
NO. 21
All areas for inpatient care, treatment and/or diagnosis, and those areas providing direct service or cleaning supplies)
2
30%
80%
(8)
(13)
Administrative, bulk storage, soiled holding, laundries and food prep areas
1
30%2
(8)
  1. 1 Based on ASHRAE 52.2.
  2. 2 Filters are not required for evaporative coolers serving laundries and food preparation areas.
  3. 3 The numbers in parentheses represent MERV rating based on ASHRAE 52.2.
407.4.1.6
Supply outlets and return and exhaust air inlets shall be located to prevent short-circuiting.
407.4.1.7 Recirculating Room Units
For spaces where Table 4-A permits air to be recirculated by room units, the portion of the minimum total air changes per hour required for a space that is greater than the minimum outdoor air changes per hour required component may be provided by recirculating room HVAC units. Such recirculating room HVAC units shall:
  1. not receive nonfiltered, nonconditioned outdoor air;
  2. serve only a single space; and
  3. provide filtration per Section 408.2 and Section 408.3 for airflow passing over any surface that is designed to condense water. This filter shall be located upstream of any such cold surface, so that all of the air passing over the cold surface is filtered.
407.5 Variable Air Volume
407.5.1 Variable Air Volume Systems (VAV)
Variable air volume systems subjecting the patient to a fluctuating air movement are not acceptable for airborne infection isolation rooms, protective environment rooms or those critically sensitive areas listed in Section 322.0. For nonsensitive areas, variable air volume systems meeting the following criteria can be considered:
407.5.1.1
The VAV system shall comply with code requirements for outside air, total air, and pressure relationship through the full range of operation from minimum to maximum.
407.5.1.2
The central return or exhaust fan shall be controlled to accomplish the variable air volume requirements of the individual rooms served by the fan as described in Section 407.5.1.3.
407.5.1.3
Spaces with pressure requirements per Table 4-A shall utilize an automatic modulating damper in the return or exhaust air for each space. The damper will modulate from full open to minimum position in conjunction with the supply air VAV terminal equipment.
407.6 Economizers
Systems with economizers shall include modulating relief and/or return fans to ensure compliance with the pressure requirements of spaces listed in Table 4-A.

Related Code Sections

407.0 Ventilation Air, Ventilation System Details
operated and such systems for areas listed in Table 4-A shall be operated continuously. Natural ventilation through windows or other openings ...
407.0 Ventilation Air, Ventilation System Details
be mechanically operated and such systems for areas listed in Table 4-A shall be operated continuously. Natural ventilation through windows or other openings ...
407.0 Ventilation Air, Ventilation System Details
be mechanically operated and such systems for areas listed in Table 4-A shall be operated continuously. Natural ventilation through windows or other openings ...
407.2 Ventilation Air, Outdoor Air Intakes and Exhaust Outlets
Outdoor air intakes shall be located at least 25 feet (7.62 m) from exhaust outlets of ventilating systems, combustion equipment stacks, medical ...
407.3 Ventilation Air, Air Balance
The ventilation systems shall be designed and balanced to provide the general air balance relationship to adjacent areas, shown in Table 4-A. The ...