Exhaled air speed measurements of respiratory air flow, generated by ten different human subjects, under uncontrolled conditions

Ivanov, M. P.

doi:10.1051/e3sconf/201911102074

Cited by 16 publications

(9 citation statements)

References 12 publications

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“…13 N). The inlet velocity was set to 0.1 m/s to simulate the exhalation velocity for nasal breathing 30 , 31 and spherical particles with a size of 5 µm have been considered for this analysis based on previous studies 32 , 33 . The velocity travels along the z-axis, from the top layer to the bottom layer for each face mask.…”

Section: Resultsmentioning

confidence: 99%

Materials analysis and image-based modelling of transmissibility and strain behaviour in approved face mask microstructures

Rasekh

Pisapia²,

Howkins

et al. 2022

Sci Rep

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Comparisons are made between six different approved face masks concerning their particle transmissibility allied to mechanical properties. The latter involves material testing and stretch or strain behaviour under load. SEM and X-ray elemental analyses showed contrasting structures between random and ordered fibre orientations. These constitute the mask designs where transmissibility is to be minimised. Airflow velocity measurement enabled filtration to be measured between the different mask designs, from two to six layers of different fabrics in combination. SEM provided the fibre diameter and pore size of each mask layer, up to a maximum of six. Stretching each complete mask showed its elasticity and recovery behaviour on an energy basis. The energy conversion involved in mask straining involves areas enclosed within steady and cyclic load-extension plots. Thus, the work done in extending a mask and the energy recovered from its release identified a hysteresis associated with an irrecoverable permanent stretch to the mask fabric. Failure of individual layers, which occurred successively in extended stretch tests, appeared as a drop in a load-extension response. That change is associated with permanent damage to each mask and friction contact within the rearrangement of loose fibre weaves. Masks with the greatest number of layers reduced particle transmissibility. However, woven or ordered mask fabrics in two layers with different orientations provided comparable performance. Simulation of each mechanical response, velocity streamlining and fibre distribution within the mask layers are also presented.

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Section: Resultsmentioning

confidence: 99%

Materials analysis and image-based modelling of transmissibility and strain behaviour in approved face mask microstructures

Rasekh

Pisapia²,

Howkins

et al. 2022

Sci Rep

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“…To assess realistic conditions, an airspeed of 0.1 m s -1 was chosen in this study. This is the maximum speed measured in 1 m distance from a human mouth after sneezing, which is the fastest air speed the human body generates at a distance of about 1 m [30] . Lower air movement speed will obviously be the condition encountered in most rooms, resulting in even higher rates of inactivation, not assessed in this study.…”

Section: Discussionmentioning

confidence: 99%

Aerosol decontamination and spatial separation using a free-space LED-based UV-C light curtain

Beyerl

Brunn

Rieker

et al. 2021

Preprint

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BackgroundThe SARS-CoV-2 pandemic demonstrated the vulnerability of our societies to aerosol transmitted pathogens. With no less than 260mio known cases and > 5mio deaths, SARS-CoV-2 is a global catastrophe leading to human and economic losses unprecedented in recent history. Thus, effective methods to limit the spread of aerosol transmitted pathogens are needed. Universal masking and curfew laws are effective but no permanent solution.MethodsA mass producible LED light source emitting homogeneous parallel UV-C light was used as a “light-barrier” to block the spread of infectious aerosols. In an aerosol test channel, Gram-negative and Gram-positive bacteria as well as coronavirus were nebulized and inactivation rates were determined.FindingsWith air speeds of 0.1 m s-1 an exposure time of 1 s in the UV-C light is obtained. Reduction in CFU for E. coli was >3log10 and for S. aureus ∼2.8log10. Plug-forming-units of the murine coronavirus (Mouse Hepatitis Virus, MHV) were reduced by about 3log10.InterpretationThe concept of a UV-C light barrier to ward off infectious aerosols if feasible and possible with a light element as described here. Coupled with sensor based activation/deactivation, such a technology could greatly reduce the transmission rates of aerosol transmitted pathogens while not disturbing natural human behaviour. This is an interesting technology allowing a “new normal” in societies after/with SARS-CoV-2.

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“…This also applies to mainstream exhaled tobacco smoke, whose particulate matter is also made of submicron liquid and solid droplets. In fact, there are studies that have directly used cigarette smoke as a tracer to visualize respiratory airflows Gupta et al (2009, 2010); Ivanov (2019). Respiratory droplets potentially carried by exhaled ECA would not change its possible role as a tracer of expiratory flows, since as we show further ahead (section 3.3) these droplets are also overwhelmingly in the submicron range and their numbers are several orders of magintude fewer than ECA droplets.…”

Section: Introductionmentioning

confidence: 87%

Modeling aerial transmission of pathogens (including the SARS-CoV-2 virus) through aerosol emissions from e-cigarettes

Sussman¹,

Golberstein²,

Polosa

2020

Preprint

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We examine the plausibility, scope and risks of aerial transmission of pathogens (including the SARS-CoV-2 virus) through respiratory droplets carried by exhaled e–cigarette aerosol (ECA). Observational and laboratory data suggests considering cigarette smoking and mouth breathing through a mouthpiece as convenient proxies to infer the respiratory mechanics and droplets sizes and their rate of emission that should result from vaping. We model exhaled ECA flow as an intermittent turbulent jet evolving into an unstable puff, estimating for low intensity vaping (practiced by 80-90% of vapers) ECA expirations the emission of 2-230 respiratory submicron droplets per puff a horizontal distance spread of 1-2 meters, with intense vaping possibly carrying hundreds and up to 1000 droplets per puff in the submicron range a distance spread over 2 meters. Bystanders exposed to low intensity expirations from an infectious vaper in indoor spaces (home and restaurant scenarios) face a 1% increase of risk with respect to a “control case” scenario defined by exclusively rest breathing without vaping. This relative added risk becomes 5−17% for high intensity vaping, 40 − 90% and over 200% for speaking or coughing (without vaping). We estimate that disinfectant properties of glycols in ECA are unlikely to act efficiently on pathogens carried by vaping expirations under realistic conditions.

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Exhaled air speed measurements of respiratory air flow, generated by ten different human subjects, under uncontrolled conditions

Cited by 16 publications

References 12 publications

Materials analysis and image-based modelling of transmissibility and strain behaviour in approved face mask microstructures

Materials analysis and image-based modelling of transmissibility and strain behaviour in approved face mask microstructures

Aerosol decontamination and spatial separation using a free-space LED-based UV-C light curtain

Modeling aerial transmission of pathogens (including the SARS-CoV-2 virus) through aerosol emissions from e-cigarettes

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