Covid-19 and aerosol transmission: up in the air

Abstract

The study of Hamilton and colleagues, to which the article refers, reports two main findings 2 Firstly, administering two types of non-invasive respiratory support to healthy volunteers led to the release of either fewer or no more aerosol particles from the respiratory tract than when coughing, speaking, and breathing normally (for continuous positive airways pressure and high flow nasal oxygen, respectively) [ ]among both healthy volunteers and inpatients with covid-19, numbers of emitted respiratory aerosols seemed higher when coughing than when breathing or speaking Another recent study has also shown the relatively low aerosol generating potential of non-invasive respiratory support 3 And coughing is well documented to produce high numbers of respiratory droplets,4 hence the role of cough in transmitting other respiratory infections including tuberculosis, the archetypal airborne disease 5 The best evidence for airborne (or aerosol) transmission of covid-19 is from outbreaks6 and through the detection of virus in air samples 7 Airborne SARS-CoV-2 has been detected in intensive care units and other general hospital areas 7 What is meant by airborne or aerosol transmission can be confusing,8 but there are now good arguments for promoting measures to reduce inhalation of the smallest droplets by exposed individuals