On Jul. 6, 2020, the lack of universal recognition that COVID-19 is transmitted via airborne particles, along with unclear infection-prevention recommendations, have led to a false sense of security that is putting the public at risk-especially amid reopenings of workplaces, schools, and colleges, according to a research letter published in Clinical Infectious Diseases.

Study authors Lidia Morawska, PhD, MSc, director of the International Laboratory for Air Quality and Health at the World Health Organization (WHO) Collaborating Centre in Brisbane, Australia, and Donald Milton, MD, DrPH, MOH, of the University of Maryland in College Park, said they implore the medical community and policymakers to acknowledge that SARS-CoV-2 can spread through the inhalation of microscopic respiratory droplets within 2 meters (6.6 feet) or close to the infectious person.

Another 237 scientists from around the world signed the research letter, which states that studies have demonstrated “beyond all reasonable doubt” that viruses released during normal breathing, talking, and coughing are small enough to remain airborne and pose an infection risk to others nearby. For example, at usual indoor airspeeds, a 5-micrometer (μm) (0.005-millimeter) particle can travel throughout a typical-sized room, settling from a height of about 1.5 meters (roughly 5 feet) onto the floor.

The authors cited a study of video records of three people infected with COVID-19 at a poorly ventilated Chinese restaurant. The videos showed no direct or indirect contact among the three parties, leading the researchers to conclude that the virus must have spread through the airborne route. And studies of other viruses such as respiratory syncytial virus (RSV) and Middle East respiratory syndrome (MERS) have shown that viruses can be exhaled and/or detected in the air of MERS isolation wards.

Acknowledging that the evidence is incomplete for all modes of coronavirus spread, including microdroplets, large droplets, and infected surfaces that are the foundation of current guidance, the authors said that the measures they propose offer more benefits than potential risks, even if only partially implemented.