TB Infection Control
Natural Ventilation for Infection Control in Health-Care Settings, WHO 2009
These are the latest WHO guidelines for natural ventilation for infection control in health-care settings. I've included below the four main recommendations featured in the executive summary.
Main recommendations
1. To help prevent airborne infections, adequate ventilation in health-care facilities in all patient-care areas is necessary.
Overall ranking: Strong recommendation
2. For natural ventilation, the following minimum hourly averaged ventilation rates should be provided:
–– 160 l/s/patient (hourly average ventilation rate) for airborne precaution rooms (with a minimum of 80 l/s/patient) (note that this only applies to new health-care facilities and major renovations;
–– 60 l/s/patient for general wards and outpatient departments; and
–– 2.5 l/s/m3 for corridors and other transient spaces without a fixed number of patients; however, when patient care is undertaken in corridors during emergency or other situations, the same ventilation rate requirements for airborne precaution rooms or general wards will apply.
The design must take into account fluctuations in ventilation rate.
When natural ventilation alone cannot satisfy the recommended ventilation requirements, alternative ventilation systems, such as hybrid (mixed-mode) natural ventilation should be considered, and then if that is not enough, mechanical ventilation should be used.
Overall ranking: Conditional recommendation
3. When designing naturally ventilated health-care facilities, overall airflow should bring the air from the agent sources to areas where there is sufficient dilution, and preferably to the outdoors.
Overall ranking: Conditional recommendation
4. For spaces where aerosol-generating procedures associated with pathogen transmission are conducted, the natural ventilation requirement should, as a minimum, follow Recommendation 2. Should the agent be airborne, Recommendations 2 and 3 should be followed.
Overall ranking: Conditional recommendation
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