We have long known that buildings play a critical role in disease transmission. COVID-19 is no different. The reason is that most of us spend most of our time inside; even prior to the COVID-19 stay-at-home orders, people around the world spent between 80% and 95% of their time indoors. Beyond that, SARS-CoV-2 transmission occurs through large droplets, infectious aerosols, and fomites (i.e. contaminated objects and surfaces). All of these routes of transmission are active in indoor environments where people may be in closer proximity to each other, sometimes breathing the same recirculated air, and touching shared objects and surfaces.

High profile explosive outbreaks have highlighted the importance of indoor transmission – from the Diamond Princess Cruise Ship to the Biogen Conference and senior homes – but the reality is that all indoor environments can pose a risk if not properly managed. Fortunately, healthy building control strategies, including increasing ventilation rates and using higher efficiency filtration, can be used in combination with other strategies in the “hierarchy of controls” to reduce the risk of COVID-19 through a layered defense approach.