Bibliographic Info
GuidelineConsolidated guidelines on the use of antiretroviral drugs for treating and preventing HIV infection: recommendations for a public health approach
Year of Publication2016
Issuing InstitutionWHO
Recommendation
Status
Updated
Recommended in favor
Strong
Certainty of evidence
Low
Administrative (facility-level infection control committee and protocols) Environmental
- Ventilation (i.e. natural and/or mechanical)
- Upper-room ultraviolet germicidal irradiation
Notes and Remarks
- 1)The threshold for ventilation requirements may vary according to the type of ventilation (e.g. recirculated air versus fresh air). There are two ways to measure ventilation rate: one uses the volume of the space (i.e. air changes per hour or ACH) while the other takes into account the number of people in a space (i.e. litres/second/person). Occupancy-based measurement of ventilation rates takes into account the fact that each person in a space should have a certain supply of fresh air. Evidence shows that for non- isolation rooms, ventilation rates lower than ACH are associated with higher TST conversion rates among staff. A higher ventilation rate is able to provide a higher dilution of airborne pathogens and consequently reduces the risk of airborne infections. The current WHO recommendation for an airborne precaution room is at least 12 ACH.b This is equivalent to 80 l/s/patient for a room of 24 m3 . WHO is updating specific guidelines on requirements for ventilation rates for different spaces (e.g. general wards, outpatient facilities, corridors); details will be provided in upcoming publications.
- 2)There have been several reports of TB transmission in health facilities with faulty or no ventilation systems. The evidence for ventilation is weak and indirect, but consistent, and it favours use of ventilation in TB infection control.
- 3)In choosing a ventilation system (i.e. natural, mixed-mode or mechanical) for health-care facilities, it is important to consider local conditions, such as building structure, climate, regulations, culture, cost and outdoor air quality. For ventilated health-care facilities, it is important to use airflow direction to minimise the risk of transmission to those susceptible to infection, although directional airflow may not be achievable with most simple natural ventilation designs. Therefore, where infectious sources are likely to be present, facility design and operation should seek to achieve airflow patterns from the source of potential contamination to the air exhaust points, or to areas where there are conditions for sufficient dilution