In this new guideline, natural ventilation is considered for the first time among the effective measures to control infections in health care. Such a recommendation from WHO demonstrates a growing recognition of the role of ventilation and natural ventilation for infection control.Previous guidelines demonstrated that further study was required in areas such as minimum requirements for natural ventilation and design, construction, operation and maintenance for effective natural ventilation systems for infection control.Over the past two years, a multidisciplinary team of engineers, architects, infection control experts and microbiologists has been working to produce this WHO guideline providing a design and operation guide for hospital planners, engineers, architects and infection-control personnel. The recommendations in this WHO guideline followed a systematic review of the literature on the association of ventilation and disease transmission, as well as effective natural ventilation solutions for infection control.