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- Alsved, Malin, et al.
(författare)
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Droplet, aerosol and SARS-CoV-2 emissions during singing and talking
- 2021
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Konferensbidrag (refereegranskat)abstract
- IntroductionAs the pandemic continues to spread, more knowledge is needed about the viral transmission routes. Several super spreading events during the Covid-19 pandemic have been linked to singing in choirs and talking loud. However, in the beginning of the pandemic there was only one study about emitted aerosols and droplets from singing, published in 1968, and only a handful on emissions from talking. Therefore, we conducted a study to measure the aerosol and droplet emissions from talking and singing. We also evaluated the emissions from singing when wearing a face mask.We have further developed our setup so that we collect the aerosol particles from Covid-19 infected patients that are talking and singing, and analyze our samples for SARS-CoV-2, the virus causing Covid-19.MethodTwelve healthy singers (7 professionals, 5 amateurs) were included in the first study part on quantifying the amount of emitted aerosols and droplets. The singers were singing or talking a short consonant rich text repeatedly at a constant pitch with their face in the opening of a funnel. The aerosol particle size and concentration was measured from the other end of the funnel using an aerodynamic particle sizer (APS, 3321, TSI Inc). In addition, the amount of un-evaporated droplets were captured with a high-speed camera and quantified using image analysis.During February and March 2021 we will collect aerosol particles from patients with confirmed Covid-19 that are singing and talking into a funnel. We will use a growth tube condensation collector, a BioSpot (Aerosol Devices), operating at 8 L min-1, and a NIOSH BC-251 cyclone sampler operating at 3.5 L min-1 (TISCH Environmental). The BioSpot collects the whole range of exhaled aerosol particles with high (95%) efficiency into liquid, and the NIOSH cyclone sampler collects particles into three size fractions: <1 µm (filter), 1-4 µm (liquid), >4 µm (liquid). The APS is again used to measure size and concentration of the emitted aerosol particles, so that emissions from infected test subjects can be compared with those of the healthy test subjects. Air samples will be analyzed for detection of SARS-CoV-2 genes, and if possible, SARS-CoV-2 infectivity in cell cultures.ResultsAerosol particle emissions from healthy test subjects were significantly higher during normal singing (median 690, range [320–2870] particles/s) than during normal talking (270 [120–1380] particles/s) (Wilcoxon’s signed rank test, p=0.002). Loud singing produced even more aerosol particles (980 [390–2870] particles/s) than normal singing (p=0.002). The amount of non-evaporated droplets detected by the high-speed camera setup showed similar results: more droplets during loud singing or talking. For both aerosol particle concentrations and droplet numbers, the levels were reduced by on average 70-80% when wearing a surgical face mask.ConclusionsSinging and talking give rise to high aerosol and droplet emissions from the respiratory tract. This is likely an important transmission route for Covid-19. In our upcoming part of the study we hope to determine how much SARS-CoV-2 that is emitted during these social activities.
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| 3. |
- Alsved, Malin, et al.
(författare)
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Exhaled respiratory particles during singing and talking
- 2020
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Ingår i: Aerosol Science and Technology. - : Informa UK Limited. - 1521-7388 .- 0278-6826. ; 54:11, s. 245-1248
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Tidskriftsartikel (refereegranskat)abstract
- Choir singing has been suspended in many countriesduring the Covid-19 pandemic due to incidental reportsof disease transmission. The mode of transmission has been attributed to exhaled droplets, but with the exception of a study on tuberculosis from1968, there is presently almost no scientific evidence ofincreased particle emissions from singing. A substantial number of studies have,however, investigated aerosols emitted from breathing,talking, coughing and sneezing. It has also been shown that justnormal breathing over time can generate more viablevirus aerosol than coughing, since the latter is a less fre-quent activity.Compared to talking, singing often involves continu-ous voicing, higher sound pressure, higher frequencies,deeper breaths, higher peak airflows and more articu-lated consonants. All these factors are likely to increaseexhaled emissions.The aim of this study was to investigate aerosol anddroplet emissions during singing, as compared to talking and breathing. We also examined the presence of SARS-CoV-2 in the air from breathing, talking and singing,and the efficacy of face masks to reduce emissions. In this study we defined aerosol particles as having a drysize in the range 0.5–10mm. Although debatable from anaerosol physics point of view, a cutoff diameter between5 and 10mm is normally used in medicine for classifica-tion of aerosol versus droplet route of transmission. Droplets are here defined as exhaled particles, frommicron size with no upper size limit, and measured dir-ectly at the mouth before complete evaporation, thuspartly in liquid phase.
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