How can airborne transmission of COVID-19 indoors be minimised?

Abstract (PubMed)

During the rapid rise in COVID-19 illnesses and deaths globally, and notwithstanding recommended precautions, questions are voiced about routes of transmission for this pandemic disease. Inhaling small airborne droplets is probable as a third route of infection, in addition to more widely recognized transmission via larger respiratory droplets and direct contact with infected people or contaminated surfaces. While uncertainties remain regarding the relative contributions of the different transmission pathways, we argue that existing evidence is sufficiently strong to warrant engineering controls targeting airborne transmission as part of an overall strategy to limit infection risk indoors. Appropriate building engineering controls include sufficient and effective ventilation, possibly enhanced by particle filtration and air disinfection, avoiding air recirculation and avoiding overcrowding. In addition, we encourage the occupants of buildings to follow public health guidance including wearing masks, to the extent appropriate, and to physically distance themselves. Simple, cost-effective steps to minimise airborne transmission of COVID-19 as part of an overall infection control strategy, alongside other precautions, include regular ventilation of enclosed spaces, avoiding overcrowding in poorly ventilated indoor spaces, use of portable air cleaners and fans, increasing fresh air supply in mechanically ventilated buildings.