Aerosol Release by Healthy People during Speaking: Possible Contribution to the Transmission of SARS-CoV-2

Abstract

Our research aimed to review the potential risk of infection by SARS-CoV-2. We used an excerpt of a data set generated in May 2020 for reviewing the SARS-CoV-2 prevention concept of orchestras, singers and actors. People were sampled for droplet release for one-hour activities using a Grimm spectrometer covering a spectrum of 1 to 32 µm diameter. We estimated the number of “quanta” in the exhaled liquid from viral concentrations of 106 to 1011/mL, based on the Human Infective Dose 50 of 218 viral particles. We employed the Wells–Riley equation to estimate the risk of infection in typical meeting rooms for a one-hour meeting of 2, 4 and 6 people observing a 2 m distance. The four participating adults released a mean of 1.28 nLm3 while breathing, 1.68 nL/m3 while speaking normally, and two adults released a mean of 4.44 nL/m3 while talking with a raised voice. The combination of 50% breathing, 45% talking normally and 5% speaking with a raised voice increased the risk of infection above 5% for a one-hour meeting of two people. The result is based on 6 quanta released, corresponding to an initial virus concentration of 1000/nL (109/mL) in the fluid of the upper respiratory tract. Our data confirm the importance of using facemasks in combination with other measures to prevent transmission of SARS-CoV-2 at the workplace.

A mask-based diagnostic platform for point-of-care screening of Covid-19

“…The difference in the Ct values between nasal swab samples and EBC is linked to the different viral load present in both fluids. ( Eiche et al, 2020 , Giovannini et al, 2021 ). Indeed, it has been postulated that the viral load of SARS-CoV-2 in aerosol samples is several orders of magnitude below those in nasopharyngeal swabs, which are in the order or 6.41 ×10 2 -1.34×10 11 copies/mL ( Giovannini et al, 2021 ).…”

Detecting SARS-CoV-2 in the Breath of COVID-19 Patients

“…Detecting virus content in breath is challenging, especially when the release concentration decreases and the sampling time is limited. Eiche and Kuster estimated the viral concentration in the exhaled liquid from 10 6 to 10 11 /mL ( 39 ) using 5-min EBC, Ma et al reported that earlier stage COVID-19 patients could exhale millions of SARS-CoV-2 particles per hour ( 23 ). The current research results show that later-stage COVID-19 patients could exhale SARS-CoV-2 at below 7,000 copies/min, corresponding to less than one copy per milliliter when considering an average exhale volume of approximately 7,000 mL/min ( 40 ).…”

Prophylactic Architecture: Formulating the Concept of Pandemic-Resilient Homes

“…There is a lot of evidence indicating that the survival time of COVID-19 in aerosols ranges from 90 min to three hours, causing the risk of airborne infection [6,27,28] as stagnant air loaded with aerosol droplets in a room with poor ven- COVID-19 is transmitted through aerosolized airborne droplets resulting from the mouth or the nose of an infected person when they breathe, speak, cough, sneeze, or sing in small liquid particles of different sizes ranging from smaller aerosols to larger respiratory droplets. People become infected when the virus enters their noses, mouths, or eyes following close direct contact with an infected person less than one meter away [6,17,[23][24][25][26][27][28][29]. Airborne viral transmission indicates the presence of microbes inside the nuclei of droplets (which are smaller than 5 µmin diameter) that can remain suspended in the air for extended periods of time and can travel over distances of more than one meter.…”

“…These aerosols (micro droplets) travel easily in enclosed, crowded and poorly ventilated spaces [6,17,24,28]. There is a lot of evidence indicating that the survival time of COVID-19 in aerosols ranges from 90 min to three hours, causing the risk of airborne infection [6,27,28] as stagnant air loaded with aerosol droplets in a room with poor ventilation may cause people who later enter the room to become infected [29]. This is valid with temperature ranging from C and humidity levels ranging from 65% to 88% according to Azuma et al, 2020 [6].…”