Aerial transmission of the SARS-CoV-2 virus through environmental e-cigarette aerosol: is it plausible?

We discuss the implications of possible contagion of COVID-19 through e-cigarette aerosol (ECA) for prevention and mitigation strategies during the current pandemic. This is a relevant issue when millions of vapers (and smokers) must remain under indoor confinement and/or share public outdoor spaces with non-users. The fact that the respiratory flow associated with vaping is visible (as opposed to other respiratory activities) clearly delineates a safety distance of 1-2 meters along the exhaled jet to prevent direct exposure. Since vaping is a relatively infrequent and intermittent respiratory activity with emission rates comparable to mouth breathing (between 2 and 230 droplets per puff), it adds into shared indoor spaces (home and restaurant scenarios) a 1% extra risk of indirect COVID-19 contagion with respect to a “control case” of existing unavoidable risk from continuous breathing. As a reference, this added relative risk increases to 44-176% for speaking 6-20 minutes per hour and 260% for coughing every 2 minutes. Mechanical ventilation, universal wearing of face masks and outdoor conditions produce marginal changes of these relative risk estimations. As a consequence, protection from possible COVID-19 contagion through vaping emissions does not require extra interventions besides the standard recommendations to the general population: keeping a social separation distance of 2 meters and wearing of face masks.