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Isolation rooms

Up Isolation rooms Negative pressure mask Resources

Claudia Cheng

Indications for use

Airborne infection isolation

  • Isolation of patients infected/suspected to be infected with organisms spread via airborne droplet nuclei <5 µm in diameter
    • eg. TB, smallpox, airborne viral diseases (eg.measles, varicella zoster), viral illnesses with as yet uncertain mode of transmission (eg. SARS, avian influenza)

Protective environment

    • Immunocompromised patients – highest risk of infection by airborne or waterborne microorganisms
    • Eg. highest risk groups are: prolonged periods of severe neutropenia (absolute neutrophil count >/=500 cells/ml)), BMT recipients, post intensive chemotherapy (eg.childhood AML), post-solid organ transplant
    • Use positive pressure rooms



  •  Patient area – should comply with standards set out in JFICM policy document IC-1 “minimum standards for intensive care units” under heading “Structure of an ICU"

  • Air-handling systems

    • Proper installation of heating, ventilation, air-conditioning; prevention of air leakages, dust accumulation

    •  Pressure differentials (negative, positive, neutral)

    •  At least 12 air changes/hr

  •  Rooms

    • Separate bathroom preferred

    • Well-sealed approximately 0.5 sq ft leakage

    •  Doors - small gap of <1/2 inch under door is sufficient for controlled airflow path

    •  Monitoring

  • Anteroom

    • Can be waived if there is a high quality negative pressure room with robust ventilation system and good pressure differential

    • To ensure appropriate air-balance relationships, help to reduce the escape of droplet nuclei during opening and closing of isolation room door

    • Also useful prompt to good infection control technique

    • Masking and unmasking should take place in the anteroom

    •  Features:

      •  independent exhaust of contaminated air to the outside, or clean to dirty airflow

      • at least12 air changes per hr

      • monitoring

      • HEPA filter (high-efficiency particulate air, remove particles down to >/= 0.3 µm) in the exhaust duct

Negative pressure isolation rooms

  • Greater exhaust than supply air volume

  • Pressure differential of 2.5 Pa

  • Windows do not open

  • Requirements

    • Clean to dirty airflow ie direction of the air flow is from the out side adjacent space (eg. corridor, anteroom) into the room

    •  Air from room preferably exhausted to the outside, but may be recirculated provided is through HEPA filter NB: recirculating air taken from areas intended to isolate a patient with TB is a risk not worth taking and is not recommended

    • Personal protective equipment for personnel entering these rooms

Positive pressure isolation rooms

  • Greater supply than exhaust air

  •  Pressure differential of 2.5 – 8 Pa, preferably 8 Pa

  • Positive air flow relative to the corridor (ie air flows from the room to the outside adjacent space)

  •  HEPA filtration, if air returned


  • Types of monitoring
    • Permanently mounted magnehelic type gauge with the reading recorded regularly (eg once a day)
    • Electronic micromanometer  linked to a remote alarm, usually by the nurses’ station
    • Observation of the direction of airflow, eg smoke tubes
  • Monitoring should be by qualified engineer, monitoring itself should be monitored.
  • Rooms frequently checked by engineer


  • Protection

    • Availability of PPE

    • Area for gowning up and removal of contaminated PPE, include mirror

    • Washing up area – additional sinks

  • Infection control practices

    • Minimize persons entering/leaving room

Further reading

CDC guidelines for environmental infection control in health-care facilities

Environmental controls: ventilation, negative pressure isolation rooms, tents and booths, air filtration and UVGI. The Control of Tuberculosis in the United Kingdom by The Interdepartmental Working Group on Tuberculosis

Minimum standards for intensive care units – JFICM policy document IC-1

© Claudia Cheng, December 2003


©Charles Gomersall, April, 2014 unless otherwise stated. The author, editor and The Chinese University of Hong Kong take no responsibility for any adverse event resulting from the use of this webpage.
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