14.3 Environmental measures in health facilities

14.3.1 Ventilation

Ventilation (natural or mechanical) is an effective means for reducing the concentration of M. tuberculosis by removing or diluting droplet nuclei suspended in air.

It is measured in air changes per hour (ACH) which is the number of times the entire volume of air in a room is replaced in one hour (for calculation of ACH, see Appendix 24). 

WHO recommends a minimum of 12 ACH in areas where TB transmission may occur (wards or rooms, diagnosis rooms, corridors, etc.) [1] Citation 1. World Health Organization. WHO policy on TB infection control in health-care facilities, congregate settings and households. World Health Organization; 2009.
https://apps.who.int/iris/bitstream/handle/10665/44148/9789241598323_eng.pdf?sequence=1 .

When planning/constructing a new TB facility or converting an existing facility, the layout of the building must maximise natural ventilation.

• It is preferable that the doors of the rooms open onto outside corridors to facilitate natural ventilation.
• If rooms are distributed along an enclosed central corridor, natural ventilation can be done by opening windows while keeping doors closed so that airflow is directed outside.
• Wind-driven roof turbines (whirly birds) can also be installed to improve natural ventilation.
• When natural ventilation is insufficient, fans can be used (assisted natural ventilation).
• Waiting areas, visiting areas and gathering spaces should be shaded outdoor areas that are open on at least three sides.
• Sputum collection areas should be located in the open air. "Sputum collection booths" (similar to voting booths) can be installed to protect patient privacy.

When adequate natural ventilation cannot be achieved (e.g. cold climate), mechanical ventilation, i.e. the use of equipment to move exhaust air from the room to the outside is necessary.

Sputum collection should be performed in very well-ventilated indoor rooms (at least 20 ACH).

Laboratories should be equipped with:

• ventilated workstation for preparing sputum smears and loading Xpert cartridges if ventilation is < 12 ACH
• biosafety cabinet if specimens are centrifuged or cut/ground regardless of the air change rate [2] Citation 2. World Health Organization. Xpert MTB/RIF implementation manual: technical and operational ‘how-to’; practical considerations. World Health Organization; 2014.
  https://apps.who.int/iris/bitstream/handle/10665/112469/9789241506700_eng.pdf .

For an overview of ventilation techniques, see Appendix 25.

For ventilated workstation and biosafety cabinet, see Appendix 6.

14.3.2 Germicidal ultraviolet lamps

Germicidal ultraviolet (GUV) lamps may be effective in killing or inactivating M. tuberculosis. When ventilation is not sufficient (i.e. does not reach 12 or 20 ACH), they should be used as a supplement to ventilation in health care facilities and congregate settings (e.g. detention centres) where the risk of TB transmission is high.

For technical information on GUV lamps see, Appendix 26.

Note: the intensity of solar radiation is variable and exposure to the sun should not be relied upon as a means of TB-IPC.