Mounting evidence suggests that tiny viral particles that linger in the air in indoor spaces are a significant source of coronavirus infection, according to 239 experts who wrote an open letter to the World Health Organization (WHO) urging the agency to issue appropriate warnings about the risks posed by the particles, known as aerosols.
The letter was published online July 6, 2020, in the journal Clinical Infectious Diseases. Signatories from Harvard T.H. Chan School of Public Health included Joseph Allen, assistant professor of exposure assessment science; Joseph Brain, Cecil K. and Philip Drinker Professor of Environmental Physiology; Philip Demokritou, associate professor of aerosol physics; Edward Nardell, professor in the Departments of Environmental Health and Immunology and Infectious Diseases; and Mary Wilson, adjunct professor of global health and population.
The authors noted that the WHO’s focus has been on hand washing, maintaining social distancing, and respiratory droplets on surfaces. While these recommendations are appropriate, they are insufficient to provide protection from virus-carrying respiratory microdroplets released into the air by infected people, particularly in enclosed or crowded environments with poor ventilation, the authors wrote.
In a July 4, 2020 New York Times article, William Hanage, associate professor of epidemiology at Harvard Chan School, noted that while some people may believe “that airborne transmission means droplets hanging in the air capable of infecting you many hours later, drifting down streets, through letter boxes and finding their way into homes everywhere,” that is not how aerosols work. Rather, the coronavirus appears to be most infectious when people are in prolonged contact at close range, especially indoors.
Read the letter in Clinical Infectious Diseases: It is Time to Address Airborne Transmission of COVID-19
Read the New York Times article: 239 Experts With One Big Claim: The Coronavirus Is Airborne