Researchers in Mexico, New Zealand and Italy have conducted a modeling study suggesting that the risk of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) being transmitted via indoor vaping is not significantly higher than the risk associated with other types of expiration.
SARS-CoV-2 is the agent responsible for the current COVID-19 pandemic that continues to sweep the globe devastating public health and the worldwide economy.
Compared with exposure to regular breathing (without vaping) within the indoor environment, exposure to low-intensity expirations from an infectious vaper only increased the risk of transmission by an additional 1%.
The relative added risk was greater for high-intensity vaping but was not as high as the added risk associated with speaking or coughing.
“Vaping is an intermittent respiratory activity whose characteristic velocities, droplet diameters and emission rates are comparable to those of breathing and lesser than those of speaking, coughing or sneezing,” write Roberto Sussman from the National Autonomous University of Mexico in Mexico City and colleagues from Myriad Pharmaceuticals Limited in Auckland and the University of Catania in Italy.
“This implies that in a shared indoor space, vaping only adds a minuscule extra contagion risk to risks already existent from rest breathing and other respiratory activities.”
A pre-print version of the paper is available on the medRxiv* server while the article undergoes peer review.
Studying the aerial transmission of SARS-CoV-2
The evolution of bioaerosols transmitting disease via respiratory droplets has already been widely studied. The COVID-19 pandemic has therefore triggered researchers to study the aerial transmission of SARS-CoV-2 via various expiratory activities, including breathing, whispering, speaking, singing, coughing, and sneezing.
Now, Sussman and team have investigated the likelihood that SARS-CoV-2 transmission could occur via a different expiratory route: exhaled e-cigarette aerosol (ECA).
“While there is currently no factual evidence that pathogens have been spread through this route, it is entirely plausible that this should occur,” they write.
What did the researchers do?
The team conducted a comprehensive study investigating the risk of contagious respiratory droplets carried by exhaled ECA, posing a risk to bystanders.
Vaping styles were divided into two main categories: the majority style (80-90 %) was low-intensity “mouth to lung” (MTL) vaping, and the minority style was high-intensity “direct to lung” (DTL) vaping.
Modeling of exhaled ECA flow showed that MTL vaping should emit an average of 2 to 230 droplets per puff across a distance of 1.0 to 2.0 meters, while DTL vaping should emit several hundred to 1,000 droplets per puff across a distance of 2.0 meters
The team estimated the relative SARS-CoV-2 contagion risk of indoor vaping (an intermittent expiratory activity) in the home and restaurant setting, compared with rest breathing - a continuous expiratory activity that can be considered a “control case” scenario.
What were the study findings?
Compared with rest breathing, low-intensity MTL vaping (160 daily puffs) only increased the relative risk of SARS-CoV-2 transmission by 1%. For high-intensity DTL vaping (160 daily puffs) the added risk was between 5 and 17 %.
For speaking 10% of the time (6 mins per hour), the added risk increased to 44%, and for speaking 40% of the time (20 mins per hour), the added risk increased to 90%. For exposure to coughing, the added risk increased to more than 260%.
What does the team advise?
Sussman and colleagues say the risk for COVID-19 contagion from indoor vaping expirations does exist and should be considered.
However, this risk must be kept in perspective with respect to the risk posed by other expiratory activities.
“As far as protection against SARS-CoV-2 virus is concerned, vaping in a home scenario or social spaces does not require special extra interventions besides those already recommended for the general population: social distance and wearing face masks,” write the researchers.
“Vapers should be advised to be alert to the worries and fears of non-vapers when sharing indoor spaces or dwellings or when close to other citizens, and for safety measures to use low-powered devices for low intensity vaping. Vapers, however, deserve the same sensitivity, courtesy, and tolerance,” advises the team.
medRxiv publishes preliminary scientific reports that are not peer-reviewed and, therefore, should not be regarded as conclusive, guide clinical practice/health-related behavior, or treated as established information.