Recomendation 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.

Population: Health-care settings

Intervention: Airflow control in natural ventilation

Quality of evidenceLowThere is moderate evidence available to suggest that incorrect airflow direction is associated with an increased risk of infection (Gustafson et al., 1982; Bloch et al., 1985; Hutton et al., 1990; Calder et al., 1991).
Benefits or desired effectsModerate (benefits sometimes outweigh disadvantages)Possibly minimized transmission risks between rooms.
Disadvantages or undesired effectsMore challenging in design and operation of the natural ventilation systems.
CostsMay be low and highLow cost if simple natural ventilation is used and properly designed with suitable climate.
Can be higher if a hybrid (mixed-mode) ventilation system or high-tech natural ventilation is used or additional engineering measures are used to control airflow direction.
FeasibilityConditional to design and controlNatural ventilation is less feasible in providing airflow control and requires careful engineering and architectural design.
Research gapThere is a need to study engineering and architectural methods for airflow control in naturally ventilated buildings.

From: Annex B, Recommendation GRADE appraisal tables (GRADE system)

Cover of Natural Ventilation for Infection Control in Health-Care Settings
Natural Ventilation for Infection Control in Health-Care Settings.
Atkinson J, Chartier Y, Pessoa-Silva CL, et al., editors.
Copyright © 2009, World Health Organization.

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