Respiratory aerosols and droplets in the transmission of infectious diseases

Pöhlker, Mira L.; Pöhlker, Christopher; Krüger, Ovid O.; Förster, Jan-David; Berkemeier, Thomas; Elbert, Wolfgang; Fröhlich-Nowoisky, Janine; Pöschl, Ulrich; Bagheri, Gholamhossein; Bodenschatz, Eberhard; Huffman, J. Alex; Scheithauer, Simone; Mikhailov, Eugene

doi:10.1103/revmodphys.95.045001

Cited by 41 publications

(23 citation statements)

References 404 publications

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“…One study comparing a spray atomizer, a reflux nebulizer, and an oscillation nebulizer reported number median particle diameters of 1.7 μm, 0.7 μm, and 1.3 μm prior to evaporation, 83 indicating that these common polydisperse particle generators operate within a similar size range. This range of particle sizes is similar to the size of nonorally produced respiratory particles produced by singing, talking, and breathing, 4 indicating that aerosols produced by these types of nebulizers are likely still of physiologically relevant diameter. Microdroplet dispensers generate series of particles individually which are typically used for single-particle techniques.…”

Section: ■ Generation Of Virus-laden Particlesmentioning

confidence: 64%

“…This generation can be described as having a large mass flux and is constrained to a monodisperse size. Because of the size of the particles typically generated by dispensers, their evaporation rates may differ from what is typical of submicron respiratory particles but are likely similar to large oral particles, 4 however, the underlying evaporation kinetics can be expected to be the same.…”

Section: ■ Generation Of Virus-laden Particlesmentioning

confidence: 99%

“…The virus suspension is a mixed solution in which virions are suspended prior to aerosolization. This solution, ideally, should be similar in composition to respiratory fluid if the study aims to determine the length of time which a virus remains infectious in realistic scenarios. ,, A virus must first be propagated in an appropriate cell line that restricts the initial composition of the virus suspension to one that is conducive to the growth of the cells. Human carcinoma-derived, or other mammalian cells that are typically used to propagate human respiratory viruses, are cultured in medium supplemented with beneficial components such as amino acids, glucose, proteins, vitamins, and antibiotics.…”

Section: Virus Suspensionmentioning

confidence: 99%

“…Through comparing diameter and geometry of airborne particles, smaller particles are expected to contain fewer viruses. 4 Understanding the competition between particle settling time and the distribution of embedded viruses is an active challenge in predicting transmission probability. 3,5−8 complicated because the particle size distribution (PSD) of respiratory particles is multimodal and the viral load within the respiratory tract is variable.…”

Section: ■ Backgroundmentioning

confidence: 99%

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Toward Standardized Aerovirology: A Critical Review of Existing Results and Methodologies

Groth,

Niazi,

Oswin

et al. 2024

Environ. Sci. Technol.

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Understanding the airborne survival of viruses is important for public health and epidemiological modeling and potentially to develop mitigation strategies to minimize the transmission of airborne pathogens. Laboratory experiments typically involve investigating the effects of environmental parameters on the viability or infectivity of a target airborne virus. However, conflicting results among studies are common. Herein, the results of 34 aerovirology studies were compared to identify links between environmental and compositional effects on the viability of airborne viruses. While the specific experimental apparatus was not a factor in variability between reported results, it was determined that the experimental procedure was a major factor that contributed to discrepancies in results. The most significant contributor to variability between studies was poorly defined initial viable virus concentration in the aerosol phase, causing many studies to not measure the rapid inactivation, which occurs quickly after particle generation, leading to conflicting results. Consistently, studies that measured their reference airborne viability minutes after aerosolization reported higher viability at subsequent times, which indicates that there is an initial loss of viability which is not captured in these studies. The composition of the particles which carry the viruses was also found to be important in the viability of airborne viruses; however, the mechanisms for this effect are unknown. Temperature was found to be important for aerosol-phase viability, but there is a lack of experiments that directly compare the effects of temperature in the aerosol phase and the bulk phase. There is a need for repeated measurements between different research groups under identical conditions both to assess the degree of variability between studies and also to attempt to better understand already published data. Lack of experimental standardization has hindered the ability to quantify the differences between studies, for which we provide recommendations for future studies. These recommendations are as follows: measuring the reference airborne viability using the "direct method"; use equipment which maximizes time resolution; quantify all losses appropriately; perform, at least, a 5-and 10-min sample, if possible; report clearly the composition of the virus suspension; measure the composition of the gas throughout the experiment. Implementing these recommendations will address the most significant oversights in the existing literature and produce data which can more easily be quantitatively compared.

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Section: ■ Generation Of Virus-laden Particlesmentioning

confidence: 64%

Section: ■ Generation Of Virus-laden Particlesmentioning

confidence: 99%

Section: Virus Suspensionmentioning

confidence: 99%

Section: ■ Backgroundmentioning

confidence: 99%

See 2 more Smart Citations

Toward Standardized Aerovirology: A Critical Review of Existing Results and Methodologies

Groth,

Niazi,

Oswin

et al. 2024

Environ. Sci. Technol.

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“…We suggest that the high aerosol concentrations detected during ventilation in cardiac arrest are due to reexpansion of collapsed airways, generating respiratory aerosol via the bronchiolar fluid film burst mode [30,31]. As collapsed alveoli re-expand, physiological fluid (surfactant and oedema) `bursts´into small particles which are expelled with the next exhalation.…”

Section: Discussionmentioning

confidence: 97%

A quantitative evaluation of aerosol generation during cardiopulmonary resuscitation

Shrimpton,

Brown,

Vassallo

et al. 2023

Anaesthesia

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SummaryIt is unclear if cardiopulmonary resuscitation is an aerosol‐generating procedure and whether this poses a risk of airborne disease transmission to healthcare workers and bystanders. Use of airborne transmission precautions during cardiopulmonary resuscitation may confer rescuer protection but risks patient harm due to delays in commencing treatment. To quantify the risk of respiratory aerosol generation during cardiopulmonary resuscitation in humans, we conducted an aerosol monitoring study during out‐of‐hospital cardiac arrests. Exhaled aerosol was recorded using an optical particle sizer spectrometer connected to the breathing system. Aerosol produced during resuscitation was compared with that produced by control participants under general anaesthesia ventilated with an equivalent respiratory pattern to cardiopulmonary resuscitation. A porcine cardiac arrest model was used to determine the independent contributions of ventilatory breaths, chest compressions and external cardiac defibrillation to aerosol generation. Time‐series analysis of participants with cardiac arrest (n = 18) demonstrated a repeating waveform of respiratory aerosol that mapped to specific components of resuscitation. Very high peak aerosol concentrations were generated during ventilation of participants with cardiac arrest with median (IQR [range]) 17,926 (5546–59,209 [1523–242,648]) particles.l‐1, which were 24‐fold greater than in control participants under general anaesthesia (744 (309–2106 [23–9099]) particles.l‐1, p < 0.001, n = 16). A substantial rise in aerosol also occurred with cardiac defibrillation and chest compressions. In a complimentary porcine model of cardiac arrest, aerosol recordings showed a strikingly similar profile to the human data. Time‐averaged aerosol concentrations during ventilation were approximately 270‐fold higher than before cardiac arrest (19,410 (2307–41,017 [104–136,025]) vs. 72 (41–136 [23–268]) particles.l‐1, p = 0.008). The porcine model also confirmed that both defibrillation and chest compressions generate high concentrations of aerosol independent of, but synergistic with, ventilation. In conclusion, multiple components of cardiopulmonary resuscitation generate high concentrations of respiratory aerosol. We recommend that airborne transmission precautions are warranted in the setting of high‐risk pathogens, until the airway is secured with an airway device and breathing system with a filter.

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Air Purifiers and Acute Respiratory Infections in Residential Aged Care

Thottiyil Sultanmuhammed Abdul Khadar,

Sim,

McDonald

et al. 2024

JAMA Netw Open

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ImportanceThe effectiveness of in-room air purification for the reduction of acute respiratory infections (ARIs) in residential aged-care facilities (RACFs) is unknown.ObjectiveTo investigate the effectiveness of in-room air purifiers with high-efficiency particulate air (HEPA)–14 filters in reducing the incidence of ARIs among residents of RACFs.Design, Setting, and ParticipantsThis randomized clinical trial used a multicenter, double-blind, 2-period, 2-treatment crossover design for 6 months from April 7 to October 26, 2023, in 3 RACFs with a bed capacity of 50 to 100 in New South Wales, Australia. The purposive sampling approach included permanent residents in private rooms in the enrolled RACFs. Data collection was performed every 2 weeks and required no additional follow-up beyond the final data collection on October 31, 2023.InterventionAn air purifier containing a HEPA-14 filter was placed in rooms of participants in the intervention group, and an air purifier without a HEPA-14 filter was placed in rooms of the control participants. The groups crossed over after 3 months.Main Outcomes and MeasuresThe primary outcome was the incidence of ARIs, assessed with logistic mixed-model regression.ResultsAmong 135 participants randomized (70 to the intervention-first group and 65 to the control-first group), 78 (57.8%) were female; mean (SD) age was 85.2 (8.6) years. In the intention-to-treat analysis, the use of air purifiers with HEPA-14 filters did not reduce ARIs compared with the control (OR, 0.57; 95% CI, 0.32-1.04; P = .07). Among the 104 participants who completed the entire study, the intervention reduced ARI incidence from 35.6% (37 participants) in the control group to 24.0% (25 participants) in the intervention group (OR, 0.53; 95% CI, 0.28-1.00; P = .048).Conclusions and RelevanceIn this clinical trial investigating use of air purifiers with HEPA-14 filters for reducing ARIs, no significant between-group difference was found in the intention-to-treat analysis. However, a significant reduction in ARIs was identified among participants who completed the entire study. These findings may help inform future large-scale studies of respiratory infectious diseases.Trial RegistrationANZCTR identification: ACTRN12623000347662

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Respiratory aerosols and droplets in the transmission of infectious diseases

Cited by 41 publications

References 404 publications

Toward Standardized Aerovirology: A Critical Review of Existing Results and Methodologies

Toward Standardized Aerovirology: A Critical Review of Existing Results and Methodologies

A quantitative evaluation of aerosol generation during cardiopulmonary resuscitation

Air Purifiers and Acute Respiratory Infections in Residential Aged Care

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