- Spaces shall be ventilated according to Table 9.1.
- Design of the ventilation system shall provide air movement that is generally from clean to less-clean areas. If any form of variable-air-volume or load-shedding system is used for energy conservation, it shall not compromise the pressure balancing relationships or the minimum air changes required by the table.
- The ventilation rates in this table are intended to provide for comfort as well as for asepsis and odor control in spaces of a health care facility that directly affect patient care. Ventilation rates for spaces not specified here shall be obtained from ANSI/ASHRAE Standard 62.11. Where spaces with prescribed rates in both Standard 62.1 and Table 9.1 of this standard exist, the higher of the two air change rates shall be used.
- For design purposes, the minimum number of total air changes indicated shall be either supplied for positive pressure rooms or exhausted for negative pressure rooms. Spaces that are required in Table 9.1 to be at a negative pressure relationship and that are not required to be exhausted shall use the supply airflow rate to compute the minimum total air changes per hour required. For spaces that require a positive or negative pressure relationship, the number of air changes can be reduced when the space is unoccupied, provided that the required pressure relationship to adjoining spaces is maintained while the space is unoccupied and that the minimum number of air changes indicated is reestablished anytime the space becomes occupied. Controls intended to switch the required pressure relationships between spaces from positive to negative, and vice versa, shall not be permitted. Air change rates in excess of the minimum values are expected in some cases in order to maintain room temperature and humidity conditions based on the space cooling or heating load.
- The entire minimum outdoor air changes per hour required by Table 9.1 for the space shall meet the filtration requirements of Section 6.4.
- For spaces where Table 9.1 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
- not receive nonfiltered, nonconditioned outdoor air;
- serve only a single space; and
- provide a minimum MERV 6 filter 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.
- For air-handling systems serving multiple spaces, system minimum outdoor air quantity shall be calculated using one of the following methods:
- System minimum outdoor air quantity for an air-handling system shall be calculated as the sum of the individual space requirements as defined by this standard.
- System minimum outdoor air quantity shall be calculated by the Ventilation Rate Procedure (multiple zone formula) of ASHRAE Standard 62.11. The minimum outdoor air change rate listed in this standard shall be interpreted as the Voz (zone outdoor airflow) for purposes of this calculation.
- Air filtration for spaces shall comply with Table 6.4.
- Supply air outlets for spaces shall comply with Table 6.7.2.
- In AII rooms, protective environment rooms, wound intensive care units (burn units), and operating and procedure rooms, heating with supply air or radiant panels that meet the requirements of Section 6.5.3 shall be provided.
|Function of Space||Pressure |
Adjacent Areas (n)
|AII Room Air |
to Outdoors (j)
|Air Recirculated |
by Means of
Room Units (a)
|SURGERY AND CRITICAL CARE|
|Critical and intensive care||NR||2||6||NR||No||30—60||70—75/21—24|
|Delivery room (Caesarean) (m), (o)||Positive||4||20||NR||No||20—60||68—75/20—24|
|Emergency department decontamination||Negative||2||12||Yes||No||NR||NR|
|Emergency department exam/treatment room (p)||NR||2||6||NR||NR||Max 60||70—75/21—24|
|Emergency department public waiting area||Negative||2||12||Yes (q)||NR||Max 65||70—75/21—24|
|Intermediate care (s)||NR||2||6||NR||NR||Max 60||70—75/21—24|
|Laser eye room||Positive||3||15||NR||No||20—60||70—75/21—24|
|Medical/anesthesia gas storage (r)||Negative||NR||8||Yes||NR||NR||NR|
|Newborn intensive care||Positive||2||6||NR||No||30—60||72—78/22—26|
|Operating room (m), (o)||Positive||4||20||NR||No||20—60||68—75/20—24|
|Operating/surgical cystoscopic rooms (m), (o)||Positive||4||20||NR||No||20—60||68—75/20—24|
|Procedure room (o), (d)||Positive||3||15||NR||No||20—60||70—75/21—24|
|Radiology waiting rooms||Negative||2||12||Yes (q), (w)||NR||Max 60||70—75/21—24|
|Substerile service area||NR||2||6||NR||No||NR||NR|
|Trauma room (crisis or shock) (c)||Positive||3||15||NR||No||20—60||70—75/21—24|
|Treatment room (p)||NR||2||6||NR||NR||20—60||70—75/21—24|
|Triage||Negative||2||12||Yes (q)||NR||Max 60||70—75/21—24|
|Wound intensive care (burn unit)||NR||2||6||NR||No||40—60||70—75/21—24|
|All anteroom (u)||(e)||NR||10||Yes||No||NR||NR|
|AII room (u)||Negative||2||12||Yes||No||Max 60||70—75/21—24|
|Combination AII/PE anteroom||(e)||NR||10||Yes||No||NR||NR|
|Combination AII/PE room||Positive||2||12||Yes||No||Max 60||70-75/21-24|
|Continued care nursery||N/R||2||6||N/R||No||30—60||72—78/22—26|
|Labor/delivery/recovery (LDR) (s)||NR||2||6||NR||NR||Max 60||70—75/21—24|
|Labor/delivery/recovery/postpartum (LDRP) (s)||NR||2||6||NR||NR||Max 60||70—75/21—24|
|Newborn nursery suite||NR||2||6||NR||No||30—60||72—78/22—26|
|Nourishment area or room||NR||NR||2||NR||NR||NR||NR|
|Patient room||NR||2||4 (y)||NR||NR||Max 60||70—75/21—24|
|PE anteroom (t)||(e)||NR||10||NR||No||NR||NR|
|Protective environment room (t)||Positive||2||12||NR||No||Max 60||70—75/21—24|
|Resident unit corridor||NR||NR||4||NR||NR||NR||NR|
|X-ray (diagnostic and treatment)||NR||2||6||NR||NR||Max 60||72—78/22—26|
|X-ray (surgery/critical care and catheterization)||Positive||3||15||NR||No||Max 60||70—75/21—24|
|DIAGNOSTIC AND TREATMENT|
|Bronchoscopy, sputum collection, and pentamidine administration||Negative||2||12||Yes||No||NR||68—73/20—23|
|Dialysis treatment area||NR||2||6||NR||NR||NR||72—78/22—26|
|Dialyzer reprocessing room||Negative||NR||10||Yes||No||NR||NR|
|ECT procedure room||NR||2||4||NR||NR||Max 60||72—78/22—26|
|Gastrointestinal endoscopy procedure room (x)||NR||2||6||NR||No||20—60||68—73/20—23|
|General examination room||NR||2||4||NR||NR||Max 60||70—75/21—24|
|Laboratory work area, bacteriology (f), (v)||Negative||2||6||Yes||NR||NR||70—75/21—24|
|Laboratory work area, biochemistry (f), (v)||Negative||2||6||Yes||NR||NR||70—75/21—24|
|Laboratory work area, cytology (f), (v)||Negative||2||6||Yes||NR||NR||70—75/21—24|
|Laboratory work area, general (f), (v)||Negative||2||6||NR||NR||NR||70—75/21—24|
|Laboratory work area, glasswashing (f)||Negative||2||10||Yes||NR||NR||NR|
|Laboratory work area, histology (f), (v)||Negative||2||6||Yes||NR||NR||70—75/21—24|
|Laboratory work area, media transfer (f), (v)||Positive||2||4||NR||NR||NR||70—75/21—24|
|Laboratory work area, microbiology (f), (v)||Negative||2||6||Yes||NR||NR||70—75/21—24|
|Laboratory work area, nuclear medicine (f), (v)||Negative||2||6||Yes||NR||NR||70—75/21—24|
|Laboratory work area, pathology (f), (v)||Negative||2||6||Yes||NR||NR||70—75/21—24|
|Laboratory work area, serology (f), (v)||Negative||2||6||Yes||NR||NR||70—75/21—24|
|Laboratory work area, sterilizing (f)||Negative||2||10||Yes||NR||NR||70—75/21—24|
|Medication room||NR||2||4||NR||NR||Max 60||70—75/21—24|
|Nonrefrigerated body-holding room (h)||Negative||NR||10||Yes||No||NR||70—75/21—24|
|Nuclear medicine hot lab||Negative||NR||6||Yes||No||NR||70—75/21—24|
|Nuclear medicine treatment room||Negative||2||6||Yes||NR||NR||70—75/21—24|
|Physical therapy||Negative||2||6||NR||NR||Max 65||72—80/22—27|
|Special examination room (aa)||NR||2||6||NR||NR||Max 60||70—75/21—24|
|Treatment room||NR||2||6||NR||NR||Max 60||70—75/21—24|
|Sterilizer equipment room||Negative||NR||10||Yes||No||NR||NR|
|STERILE PROCESSING DEPARTMENTz|
|Clean workroom||Positive||2||4||NR||No||Max 60||68—73/20—23|
|Sterile storage room||Positive||2||4||NR||NR||Max 60||Max 75/24|
|Clean linen storage||Positive||NR||2||NR||NR||NR||72—78/22—26|
|Food preparation center (i)||NR||2||10||NR||No||NR||72—78/22—26|
|Linen and trash chute room||Negative||NR||10||Yes||No||NR||NR|
|Soiled linen sorting and storage||Negative||NR||10||Yes||No||NR||NR|
|Clean workroom or clean holding||Positive||2||4||NR||NR||NR||NR|
|Hazardous material storage||Negative||2||10||Yes||No||NR||NR|
|Soiled workroom or soiled holding||Negative||2||10||Yes||No||NR||NR|
- a. Except where indicated by a "No" in this column, recirculating room HVAC units (with heating or cooling coils) are acceptable for providing that portion of the minimum total air changes per hour that is permitted by Section 9.1 (subparagraph [a]). Because of the cleaning difficulty and potential for buildup of contamination, recirculating room units shall not be used in areas marked "No." Recirculating devices with high-efficiency particulate air (HEPA) filters shall be permitted in existing facilities as interim, supplemental environmental controls to meet requirements for the control of airborne infectious agents. The design of either portable or fixed systems should prevent stagnation and short circuiting of airflow. The design of such systems shall also allow for easy access for scheduled preventative maintenance and cleaning.
- b. Pharmacy compounding areas may have additional air change, differential pressure, and filtering requirements beyond the minimum of this table, depending on the type of pharmacy, the regulatory requirements (which may include adoption of USP-797), the associated level of risk of the work, and the equipment used in the spaces. Informative Note: See USP (2017a) in Appendix B.
- c. The term trauma room as used herein is a first-aid room and/or emergency department room used for general initial treatment of accident victims. The OR within the trauma center that is routinely used for emergency surgery is considered to be an OR by this standard.
- d. Pressure relationships need not be maintained when the room is unoccupied.
- e. See Section 9.2 and its subsections for pressure relationship requirements.
- f. Higher ventilation rates above the total ach listed shall be used when dictated by the laboratory program requirements and the hazard level of the potential contaminants in each laboratory work area. Lower total ach ventilation rates shall be permitted when a Hazard Assessment performed as part of an effective Laboratory Ventilation Management Plan per ANSI/AIHA/ASSE Z9.5, American National Standard for Laboratory Ventilation13 determines that either (a) acceptable exposure concentrations in the laboratory work area can be achieved with a lower minimum total ach ventilation rate than is listed in Table 9.1 or (b) a demand control approach with active sensing of contaminants or appropriate surrogates is used as described in ASHRAE Handbook-HVAC Applications, Chapter 16, "Laboratories" (Informative Note: See ASHRAE  in Informative Appendix B).
- g. All air need not be exhausted if darkroom equipment has a scavenging exhaust duct attached and meets ventilation standards regarding NIOSH5, OSHA, and local employee exposure limits.
- h. A nonrefrigerated body-holding room is applicable only to facilities that do not perform autopsies on-site and use the space for short periods while waiting for the body to be transferred.
- i. Minimum total air changes per hour (ach) shall be that required to provide proper makeup air to kitchen exhaust systems as specified in ANSI/ASHRAE Standard 1546. In some cases, excess exfiltration or infiltration to or from exit corridors compromises the exit corridor restrictions of NFPA 90A7, the pressure requirements of NFPA 968, or the maximum defined in the table. During operation, a reduction to the number of air changes to any extent required for odor control shall be permitted when the space is not in use.
- j. In some areas with potential contamination and/or odor problems, exhaust air shall be discharged directly to the outdoors and not recirculated to other areas. Individual circumstances may require special consideration for air exhausted to the outdoors. To satisfy exhaust needs, constant replacement air from the outdoors is necessary when the system is in operation.
- k. The RH ranges listed are the minimum and/or maximum allowable at any point within the design temperature range required for that space.
- l. Systems shall be capable of maintaining the rooms within the range during normal operation. Lower or higher temperature shall be permitted when patients' comfort and/or medical conditions require those conditions.
- m. National Institute for Occupational Safety and Health (NIOSH) criteria documents9 regarding occupational exposure to waste anesthetic gases and vapors and control of occupational exposure to nitrous oxide indicate a need for both local exhaust (scavenging) systems and general ventilation of the areas in which the respective gases are used. Refer to NFPA 9910 for other requirements.
- n. If pressure-monitoring device alarms are installed, allowances shall be made to prevent nuisance alarms. Short-term excursions from required pressure relationships shall be allowed while doors are moving or temporarily open. Simple visual methods such as smoke trail, ball-in-tube, or flutterstrip shall be permitted for verification of airflow direction.
- o. Surgeons or surgical procedures may require room temperatures, ventilation rates, humidity ranges, and/or air distribution methods that exceed the minimum indicated ranges.
- p. Treatment rooms used for bronchoscopy shall be treated as bronchoscopy rooms. Treatment rooms used for procedures with nitrous oxide shall contain provisions for exhausting anesthetic waste gases.
- q. In a recirculating ventilation system, HEPA filters shall be permitted instead of exhausting the air from these spaces to the outdoors, provided that the return air passes through the HEPA filters before it is introduced into any other spaces. The entire minimum total air changes per hour of recirculating airflow shall pass through HEPA filters. When these areas are open to larger, nonwaiting spaces, the exhaust air volume shall be calculated based on the seating area of the waiting area. Informative Note: The intent here is to not require the volume calculation to include a very large space (e.g., an atrium) just because a waiting area opens onto it.
- r. See NFPA 9910 for further requirements.
- s. For intermediate care, labor/delivery/recovery rooms, and labor/delivery/recovery/postpartum rooms, four total ach shall be permitted when supplemental heating and/or cooling systems (radiant heating and cooling, baseboard heating, etc.) are used.
- t. The protective environment airflow design specifications protect the patient from common environmental airborne infectious microbes (i.e., Aspergillus spores). Recirculation HEPA filters shall be permitted to increase the equivalent room air exchanges; however, the outdoor air changes are still required. Constant-volume airflow is required for consistent ventilation for the protected environment. The pressure relationship to adjacent areas shall remain unchanged if the protective environment (PE) room is used as a normal patient room. Rooms with reversible airflow provisions for the purpose of switching between protective environment and All functions shall not be permitted.
- u. The AII room described in this standard shall be used for isolating the airborne spread of infectious diseases, such as measles, varicella, or tuberculosis. Supplemental recirculating devices using HEPA filters shall be permitted in the AII room to increase the equivalent room air exchanges; however, the minimum outdoor air changes of Table 9.1 are still required. AII rooms that are retrofitted from standard patient rooms from which it is impractical to exhaust directly outdoors may be recirculated with air from the AII room, provided that air first passes through a HEPA filter. When the AII room is not used for airborne infection isolation, the pressure relationship to adjacent areas, when measured with the door closed, shall remain unchanged, and the minimum total air change rate shall be 6 ach.
- v. Room temperature ranges that exceed the minimum indicated range shall be permitted if required by the laboratory program or laboratory equipment.
- w. The requirement that all room air is exhausted directly to outdoors applies only to radiology waiting rooms programmed to hold patients who are waiting for chest x-rays for diagnosis of respiratory disease.
- x. If the planned space is designated in the organization's operational plan to be used for both bronchoscopy and gastrointestinal endoscopy, the design parameters for "bronchoscopy, sputum collection, and pentamidine administration" shall be used.
- y. For single-bed patient rooms using Group D diffusers, a minimum of six total ach shall be provided and calculated based on the volume from finished floor to 6 ft (1.83 m) above the floor.
- z. See AAMI Standard ST7911 for additional information for these spaces.
- aa. Examination rooms programmed for use by patients with undiagnosed gastrointestinal symptoms, undiagnosed respiratory symptoms, or undiagnosed skin symptoms.
- Each AII room shall comply with requirements of Tables 6.4, 6.7.2, and 9.1. AII rooms shall have a permanently installed device and/or mechanism to constantly monitor the differential air pressure between the room (when occupied by patients with a suspected airborne infectious disease) and the corridor, whether or not there is an anteroom. A local visual means shall be provided to indicate whenever negative differential pressure is not maintained.
- All air from the AII room shall be exhausted directly to the outdoors. Exception to 9.2.1(b): AII rooms that are retrofitted from standard patient rooms from which it is impractical to exhaust directly outdoors may be provided with recirculated air from the room's exhaust on the condition that the air first passes through a HEPA filter.
- All exhaust air from the AII rooms, associated anterooms, and associated toilet rooms shall be discharged directly to the outdoors without mixing with exhaust air from any other non-AII room or exhaust system.
- Exhaust air grilles or registers in the patient room shall be located directly above the patient bed, on the ceiling or on the wall near the head of the bed, unless it can be demonstrated that such a location is not practical.
- The room envelope shall be sealed to provide a minimum differential pressure of 0.01 in. of water (2.5 Pa) across the envelope.
- Differential pressure between AII rooms and adjacent spaces that are not AII rooms shall be a minimum of —0.01 in. of water (—2.5 Pa). Spaces such as the toilet room and the anteroom (if present) that are directly associated with the AII room and open directly into the AII room are not required to be designed with a minimum pressure difference from the AII room but are still required to maintain the pressure relationships to adjacent areas specified in Table 9.1.
- When an anteroom is provided, the pressure relationships shall be as follows: (1) the AII room shall be at a negative pressure with respect to the anteroom, and (2) the anteroom shall be at a negative pressure with respect to the corridor.
- The room envelope shall be sealed to provide a minimum differential pressure of 0.01 in. of water (2.5 Pa) across the envelope.
- Each PE room shall comply with the requirements of Tables 6.4, 6.7.2, and 9.1. When occupied by patients requiring a protective environment, PE rooms shall have a permanently installed device and/or mechanism to constantly monitor the differential air pressure between the room and the corridor, regardless of whether there is an anteroom. A local visual means shall be provided to indicate whenever positive differential pressure is not maintained.
- Air distribution patterns within the protective environment room shall conform to the following:
- Supply air diffusers shall be located above the patient bed unless it can be demonstrated that such a location is not practical. Diffuser design shall limit air velocity at the patient bed to reduce patient discomfort. Informative Note: See ASHRAE (2017b) in Appendix B.
- Return/exhaust grilles or registers shall be located near the patient room door.
- Differential pressure between PE rooms and adjacent spaces that are not PE rooms shall be a minimum of +0.01 in. of water (+2.5 Pa). Spaces such as the toilet room and the anteroom (if present) that are directly associated with the PE room and open directly into the PE room are not required to be designed with a minimum pressure difference from the PE room but are still required to maintain the pressure relationships to adjacent areas specified in Table 9.1.
- PE rooms retrofitted from standard patient rooms may be ventilated with recirculated air, provided that air first passes through a HEPA filter and the room complies with Section 9.2.2(a) through 9.2.2(d).
- When an anteroom is provided, the pressure relationships shall be as follows: (1) the PE room shall be at a positive pressure with respect to the anteroom, and (2) the anteroom shall be at a positive pressure with respect to the corridor.
- Supply air diffusers shall be located above the patient bed.
- Exhaust grilles or registers shall be located near the patient room door.
- The pressure relationship to adjacent areas for the required anteroom shall be one of the following:
- The anteroom shall be at a positive pressure with respect to both the AII/PE room and the corridor or common space.
- The anteroom shall be at a negative pressure with respect to both the AII/PE room and the corridor or common space.
- AII/PE rooms shall have two permanently installed devices and/or mechanisms to constantly monitor the differential air pressure. One device and/or mechanism shall monitor the pressure differential between the AII/PE room and the anteroom. The second device and/or mechanism shall monitor the pressure differential between the anteroom and the corridor or common space. For each device and/or mechanism, a local visual means shall be provided to indicate whenever differential pressure is not maintained.
- The airflow shall be unidirectional, downwards, and the average velocity of the diffusers shall be 25 to 35 cfm/ft2 (127 to 178 L/s/m2). The diffusers shall be concentrated to provide an airflow pattern over the patient and surgical team. Informative Note: For more information, see Memarzadeh and Manning (2002) and Memarzadeh and Jiang (2004) in Appendix B.
- The coverage area of the primary supply diffuser array shall extend a minimum of 12 in. (305 mm) beyond the footprint of the surgical table on each side. Within the portion of the primary supply diffuser array that consists of an area encompassing 12 in. (305 mm) on each side of the footprint of the surgical table, no more than 30% of this portion of the primary supply diffuser array area shall be used for nondiffuser uses such as lights, gas columns, equipment booms, access panels, sprinklers, etc.
- Low sidewall exhaust grilles shall be provided unless exhaust air is removed through an autopsy table designed for this purpose.
- All exhaust air from autopsy, nonrefrigerated body holding, and morgue rooms shall be discharged directly to the outdoors without mixing with air from any other room or exhaust system.
- Differential pressure between morgue and autopsy rooms and any adjacent spaces that have other functions shall be a minimum of —0.01 in. of water (—2.5 Pa).
- Differential pressure between bronchoscopy procedure and sputum induction rooms and any adjacent spaces that have other functions shall be a minimum of —0.01 in. of water (—2.5Pa).
- Local exhaust shall be provided for sputum collection procedures.