Particle sizes of infectious aerosols: implications for infection control
Author
Fennelly, Kevin P
Institutions
Abstract
The global pandemic of COVID-19 has been associated with infections and deaths among health-care workers. This
Viewpoint of infectious aerosols is intended to inform appropriate infection control measures to protect health-care
workers. Studies of cough aerosols and of exhaled breath from patients with various respiratory infections have
shown striking similarities in aerosol size distributions, with a predominance of pathogens in small particles (<5 µm).
These are immediately respirable, suggesting the need for personal respiratory protection (respirators) for individuals
in close proximity to patients with potentially virulent pathogens. There is no evidence that some pathogens are
carried only in large droplets. Surgical masks might offer some respiratory protection from inhalation of infectious
aerosols, but not as much as respirators. However, surgical masks worn by patients reduce exposures to infectious
aerosols to health-care workers and other individuals. The variability of infectious aerosol production, with some socalled super-emitters producing much higher amounts of infectious aerosol than most, might help to explain the
epidemiology of super-spreading. Airborne infection control measures are indicated for potentially lethal respiratory
pathogens such as severe acute respiratory syndrome coronavirus 2.