experiments are ongoing to determine viral activity in the collected samples.1

An airflow modeling study following the SARS-CoV-1 outbreak in Hong Kong in the early 2000s supports the potential for transmission via bioaerosols. In that study, the significantly increased risk of infection to residents on higher floors of a building that was home to an infected individual indicated to the researchers a pattern of infection consistent with a rising plume of contaminated warm air.2

In a recent study conducted at the University of Hong Kong, not yet subject to peer review, Leung et al collected respiratory droplets and aerosols from children and adults with acute respiratory illnesses with and without surgical masks. The investigators found human coronaviruses [other than SARS-CoV-2], influenza virus, and rhinovirus from both aerosols and respiratory droplets. Surgical masks reduced detection of coronavirus RNA in both respiratory droplets and aerosols, but only respiratory droplets and not aerosols for influenza virus RNA. These findings suggest that surgical face masks could reduce the transmission of human coronavirus and influenza infections if worn by infected individuals capable of transmitting the infection.3

A study of SARS-CoV-2 raises concerns about transmission via aerosols generated from droplet contaminated surfaces. Liu et al. collected 35 aerosol samples in 2 hospitals and public areas in Wuhan. From samples collected in patient care areas the highest concentration of the virus was found in toilet facilities (19 copies m–3), and in medical staff areas the highest concentrations were identified in personal protective equipment (PPE) removal rooms (18-42 copies m–3). By comparison, in all but two crowded sites, the concentrations of the virus found in public areas was below 3 copies m–3. The authors conclude that a direct source of SARS-CoV-2 may be a virus-laden aerosol resuspended by the doffing of PPE, the cleaning of floors, or the movement of staff.4 It may be difficult to resuspend particles of a respirable size. However, fomites could be transmitted to the hands, mouth, nose, or eyes without requiring direct respiration into the lungs.

Individuals vary in the degree to which they produce bioaerosols through normal breathing.5 This may have a bearing on efficiency of transmission of SARS-CoV-2 by different infected but asymptomatic individuals.

Additional research specific to the aerosolization of SARS-CoV-2 during breathing and speech, the behavior of SARS-CoV-2 containing aerosols in the environment, both from laboratory studies and clinical experience, and the infectivity of bioaerosols containing SARS-CoV-2,

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