Emission rates, size distributions, and generation mechanism of oral respiratory droplets

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has brought renewed attention to respiratory aerosol and droplet generation. While many studies have robustly quantified aerosol (<10 µm diameter) number and mass exhalation rates, fewer studies have explored larger droplet generation. This study quantifies respiratory droplets (>20 µm diameter) generated by a cohort of 76 adults and children using a water-sensitive paper droplet deposition approach. Unvoiced and voiced activities spanning different levels of loudness, different lengths of sustained phonation, and a specific manner of articulation in isolation were investigated. We find that oral articulation drives >20 µm droplet generation, with breathing generating virtually no droplets and speaking and singing generating on the order of 250 droplets min−1. Lip trilling, which requires extensive oral articulation, generated the most droplets, whereas shouting "Hey,” which requires minimal oral articulation, generated relatively few droplets. Droplet size distributions were all broadly consistent, and no significant differences between the children and adult cohorts were identified. By comparing the aerosol and droplet emissions for the same participants, the full size distribution of respiratory aerosol (0.5–1000 µm) is reported. Although <10 µm aerosol dominates the number concentration, >20 µm droplets dominate the mass concentration. Accurate quantification of aerosol concentrations in the 10–70 μm size range remains very challenging;more robust aerosol analysis approaches are needed to characterize this size range.

Emission Rates, Size Distributions, and Generation Mechanism of Oral Respiratory Droplets

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has brought renewed attention to respiratory aerosol and droplet generation. While many studies have robustly quantified aerosol (<10 µm diameter) number and mass exhalation rates, fewer studies have explored larger droplet generation. This study quantifies respiratory droplets (>20 µm diameter) generated by a cohort of 76 adults and children using a water-sensitive paper droplet deposition approach. Unvoiced and voiced activities spanning different levels of loudness, different lengths of sustained phonation, and a specific manner of articulation in isolation were investigated. We find that oral articulation drives >20 µm droplet generation, with breathing generating virtually no droplets and speaking and singing generating on the order of 250 droplets min−1. Lip trilling, which requires extensive oral articulation, generated the most droplets, whereas shouting "Hey”, which requires minimal oral articulation, generated relatively few droplets. Droplet size distributions were all broadly consistent, and no significant differences between the children and adult cohorts were identified. By comparing the aerosol and droplet emissions for the same participants, the full size distribution of respiratory aerosol (0.5-1000 µm) is reported. Although <10 µm aerosol dominates the number concentration, >20 µm droplets dominate the mass concentration. Accurate quantification of aerosol concentrations in the 10-70 μm size range remains very challenging;more robust aerosol analysis approaches are needed to characterize this size range. [ FROM AUTHOR]

Reporting of data on participant ethnicity and socioeconomic status in high-impact medical journals: a targeted literature review.

OBJECTIVES: To assess the frequency of reporting of ethnicity (or 'race') and socioeconomic status (SES) indicators in high-impact journals. DESIGN: Targeted literature review. DATA SOURCES: The 10 highest ranked general medical journals using Google scholar h5 index. ELIGIBILITY CRITERIA: Inclusion criteria were, human research, reporting participant level data. Exclusion criteria were non-research article, animal/other non-human participant/subject or no participant characteristics reported. DATA EXTRACTION AND SYNTHESIS: Working backwards from 19 April 2021 in each journal, two independent reviewers selected the 10 most recent articles meeting inclusion/exclusion criteria, to create a sample of 100 articles. Data on the frequency of reporting of ethnicity (or 'race') and SES indicators were extracted and presented using descriptive statistics. RESULTS: Of 100 research articles included, 35 reported ethnicity and 13 SES. By contrast, 99 reported age, and 97 reported sex or gender. Among the articles not reporting ethnicity, only 3 (5%) highlighted this as a limitation, and only 6 (7%) where SES data were missing. Median number of articles reporting ethnicity per journal was 2.5/10 (range 0 to 9). Only two journals explicitly requested reporting of ethnicity (or race), and one requested SES. CONCLUSIONS: The majority of research published in high-impact medical journals does not include data on the ethnicity and SES of participants, and this omission is rarely acknowledged as a limitation. This situation persists despite the well-established importance of this issue and International Committee of Medical Journal Editors recommendations to include relevant demographic variables to ensure representative samples. Standardised explicit minimum standards are required.

A comparison of respiratory particle emission rates at rest and while speaking or exercising.

Background: The coronavirus disease-19 (COVID-19) pandemic led to the prohibition of group-based exercise and the cancellation of sporting events. Evaluation of respiratory aerosol emissions is necessary to quantify exercise-related transmission risk and inform mitigation strategies. Methods: Aerosol mass emission rates are calculated from concurrent aerosol and ventilation data, enabling absolute comparison. An aerodynamic particle sizer (0.54-20 µm diameter) samples exhalate from within a cardiopulmonary exercise testing mask, at rest, while speaking and during cycle ergometer-based exercise. Exercise challenge testing is performed to replicate typical gym-based exercise and very vigorous exercise, as determined by a preceding maximally exhaustive exercise test. Results: We present data from 25 healthy participants (13 males, 12 females; 36.4 years). The size of aerosol particles generated at rest and during exercise is similar (unimodal ~0.57-0.71 µm), whereas vocalization also generated aerosol particles of larger size (i.e. was bimodal ~0.69 and ~1.74 µm). The aerosol mass emission rate during speaking (0.092 ng s-1; minute ventilation (VE) 15.1 L min-1) and vigorous exercise (0.207 ng s-1, p = 0.726; VE 62.6 L min-1) is similar, but lower than during very vigorous exercise (0.682 ng s-1, p < 0.001; VE 113.6 L min-1). Conclusions: Vocalisation drives greater aerosol mass emission rates, compared to breathing at rest. Aerosol mass emission rates in exercise rise with intensity. Aerosol mass emission rates during vigorous exercise are no different from speaking at a conversational level. Mitigation strategies for airborne pathogens for non-exercise-based social interactions incorporating vocalisation, may be suitable for the majority of exercise settings. However, the use of facemasks when exercising may be less effective, given the smaller size of particles produced.

An online breathing and wellbeing programme (ENO Breathe) for people with persistent symptoms following COVID-19: a parallel-group, single-blind, randomised controlled trial.

BACKGROUND: There are few evidence-based interventions for long COVID; however, holistic approaches supporting recovery are advocated. We assessed whether an online breathing and wellbeing programme improves health related quality-of-life (HRQoL) in people with persisting breathlessness following COVID-19. METHODS: We conducted a parallel-group, single-blind, randomised controlled trial in patients who had been referred from one of 51 UK-based collaborating long COVID clinics. Eligible participants were aged 18 years or older; were recovering from COVID-19 with ongoing breathlessness, with or without anxiety, at least 4 weeks after symptom onset; had internet access with an appropriate device; and were deemed clinically suitable for participation by one of the collaborating COVID-19 clinics. Following clinical assessment, potential participants were given a unique online portal code. Participants were randomly assigned (1:1) to either immediate participation in the English National Opera (ENO) Breathe programme or to usual care. Randomisation was done by the research team using computer-generated block randomisation lists, with block size 10. The researcher responsible for randomisation was masked to responses. Participants in the ENO Breathe group participated in a 6-week online breathing and wellbeing programme, developed for people with long COVID experiencing breathlessness, focusing on breathing retraining using singing techniques. Those in the deferred group received usual care until they exited the trial. The primary outcome, assessed in the intention-to-treat population, was change in HRQoL, assessed using the RAND 36-item short form survey instrument mental health composite (MHC) and physical health composite (PHC) scores. Secondary outcome measures were the chronic obstructive pulmonary disease assessment test score, visual analogue scales (VAS) for breathlessness, and scores on the dyspnoea-12, the generalised anxiety disorder 7-item scale, and the short form-6D. A thematic analysis exploring participant experience was also conducted using qualitative data from focus groups, survey responses, and email correspondence. This trial is registered with ClinicalTrials.gov, NCT04830033. FINDINGS: Between April 22 and May 25, 2021, 158 participants were recruited and randomly assigned. Of these, eight (5%) individuals were excluded and 150 participants were allocated to a treatment group (74 in the ENO Breathe group and 76 in the usual care group). Compared with usual care, ENO Breathe was associated with an improvement in MHC score (regression coefficient 2·42 [95% CI 0·03 to 4·80]; p=0·047), but not PHC score (0·60 [-1·33 to 2·52]; p=0·54). VAS for breathlessness (running) favoured ENO Breathe participation (-10·48 [-17·23 to -3·73]; p=0·0026). No other statistically significant between-group differences in secondary outcomes were observed. One minor self-limiting adverse event was reported by a participant in the ENO Breathe group who felt dizzy using a computer for extended periods. Thematic analysis of ENO Breathe participant experience identified three key themes: (1) improvements in symptoms; (2) feeling that the programme was complementary to standard care; and (3) the particular suitability of singing and music to address their needs. INTERPRETATION: Our findings suggest that an online breathing and wellbeing programme can improve the mental component of HRQoL and elements of breathlessness in people with persisting symptoms after COVID-19. Mind-body and music-based approaches, including practical, enjoyable, symptom-management techniques might have a role supporting recovery. FUNDING: Imperial College London.

Factors shaping the mental health and well-being of people experiencing persistent COVID-19 symptoms or 'long COVID': qualitative study.

BACKGROUND: Around one in ten people who contract COVID-19 report persistent symptoms or 'long COVID'. Impaired mental health and well-being is commonly reported, including anxiety, depression and reduced quality of life. However, there is limited in-depth research exploring why mental health and well-being are affected in people experiencing long COVID. AIMS: To explore factors affecting mental health and well-being from the perspective of people with long COVID. METHOD: Semi-structured qualitative interviews were audio-recorded and transcribed. Data were analysed using reflexive thematic analysis. Twenty-one people with long COVID participated in the study. Participants were eligible if they self-reported a positive swab test/antibody test or one or more commonly reported COVID-19 symptoms at illness onset. and experiences of one or more long COVID symptoms ≥3 weeks following illness onset. RESULTS: Five themes were identified across participant accounts regarding factors affecting mental health and well-being, including symptoms causing severe disruption to daily life, lack of service and treatment options, uncertainty of illness trajectories, experiences of care and understanding from others and changes to identity. CONCLUSIONS: People with long COVID experience a range of factors that negatively affect their mental health and well-being. Providing patient-centred health services that integrate rapidly evolving research in this area is important, as are peer support groups and supported approaches to self-management.

Comparing aerosol number and mass exhalation rates from children and adults during breathing, speaking and singing.

Aerosol particles of respirable size are exhaled when individuals breathe, speak and sing and can transmit respiratory pathogens between infected and susceptible individuals. The COVID-19 pandemic has brought into focus the need to improve the quantification of the particle number and mass exhalation rates as one route to provide estimates of viral shedding and the potential risk of transmission of viruses. Most previous studies have reported the number and mass concentrations of aerosol particles in an exhaled plume. We provide a robust assessment of the absolute particle number and mass exhalation rates from measurements of minute ventilation using a non-invasive Vyntus Hans Rudolf mask kit with straps housing a rotating vane spirometer along with measurements of the exhaled particle number concentrations and size distributions. Specifically, we report comparisons of the number and mass exhalation rates for children (12-14 years old) and adults (19-72 years old) when breathing, speaking and singing, which indicate that child and adult cohorts generate similar amounts of aerosol when performing the same activity. Mass exhalation rates are typically 0.002-0.02 ng s-1 from breathing, 0.07-0.2 ng s-1 from speaking (at 70-80 dBA) and 0.1-0.7 ng s-1 from singing (at 70-80 dBA). The aerosol exhalation rate increases with increasing sound volume for both children and adults when both speaking and singing.

Patient symptoms and experience following COVID-19: results from a UK-wide survey.

OBJECTIVES: To investigate the experience of people who continue to be unwell after acute COVID-19, often referred to as 'long COVID', both in terms of their symptoms and their interactions with healthcare. DESIGN: We conducted a mixed-methods analysis of responses to a survey accessed through a UK online post-COVID-19 support and information hub, between April and December 2020, about people's experiences after having acute COVID-19. PARTICIPANTS: 3290 respondents, 78% female, 92.1% white ethnicity and median age range 45-54 years; 12.7% had been hospitalised. 494(16.5%) completed the survey between 4 and 8 weeks of the onset of their symptoms, 641(21.4%) between 8 and 12 weeks and 1865 (62.1%) >12 weeks after. RESULTS: The ongoing symptoms most frequently reported were: breathing problems (92.1%), fatigue (83.3%), muscle weakness or joint stiffness (50.6%), sleep disturbances (46.2%), problems with mental abilities (45.9%), changes in mood, including anxiety and depression (43.1%) and cough (42.3%). Symptoms did not appear to be related to the severity of the acute illness or to the presence of pre-existing medical conditions. Analysis of free-text responses revealed three main themes: (1) experience of living with COVID-19: physical and psychological symptoms that fluctuate unpredictably; (2) interactions with healthcare that were unsatisfactory; (3) implications for the future: their own condition, society and the healthcare system, and the need for research CONCLUSION: Consideration of patient perspectives and experiences will assist in the planning of services to address problems persisting in people who remain symptomatic after the acute phase of COVID-19.

Acceptability of hygiene, face covering and social distancing interventions to prevent exacerbations in people living with airways diseases.

Interventions to prevent the spread of SARS-CoV-2 have been associated with substantial reductions in exacerbations of airways diseases, likely through reduced transmission of other respiratory viruses. We surveyed 4442 people with airways disease (asthma=3627, bronchiectasis=258, chronic obstructive pulmonary disease=557) to gauge attitudes and intentions towards continuing such measures after the COVID-19 pandemic. 47% intended to continue wearing a face mask in indoor public spaces, and 61% thought everyone should be required to do so during the 'influenza season. Women, those with bronchiectasis, and older people were generally more cautious. Respiratory virus infection control measures should be considered in clinical guidelines and public health recommendations.

CT Lung Abnormalities after COVID-19 at 3 Months and 1 Year after Hospital Discharge.

Background Data on the long-term pulmonary sequelae in COVID-19 are lacking. Purpose To assess symptoms, functional impairment, and residual pulmonary abnormalities on serial chest CT scans in COVID-19 survivors discharged from hospital at up to 1-year follow-up. Materials and Methods Adult patients with COVID-19 discharged between March 2020 and June 2020 were prospectively evaluated at 3 months and 1 year through systematic assessment of symptoms, functional impairment, and thoracic CT scans as part of the PHENOTYPE study, an observational cohort study in COVID-19 survivors. Lung function testing was limited to participants with CT abnormalities and/or persistent breathlessness. Bonferroni correction was used. Results Eighty participants (mean age, 59 years ± 13 [SD]; 53 men) were assessed. At outpatient review, persistent breathlessness was reported in 37 of the 80 participants (46%) and cough was reported in 17 (21%). CT scans in 73 participants after discharge (median, 105 days; IQR, 95-141 days) revealed persistent abnormalities in 41 participants (56%), with ground-glass opacification (35 of 73 participants [48%]) and bands (27 of 73 participants [37%]) predominating. Unequivocal signs indicative of established fibrosis (ie, volume loss and/or traction bronchiectasis) were present in nine of 73 participants (12%). Higher admission serum C-reactive protein (in milligrams per liter), fibrinogen (in grams per deciliter), urea (millimoles per liter), and creatinine (micromoles per liter) levels; longer hospital stay (in days); older age (in years); and requirement for invasive ventilation were associated with CT abnormalities at 3-month follow-up. Thirty-two of 41 participants (78%) with abnormal findings at 3-month follow-up CT underwent repeat imaging at a median of 364 days (range, 360-366 days), with 26 (81%) showing further radiologic improvement (median, 18%; IQR, 10%-40%). Conclusion CT abnormalities were common at 3 months after COVID-19 but with signs of fibrosis in a minority. More severe acute disease was linked with CT abnormalities at 3 months. However, radiologic improvement was seen in the majority at 1-year follow-up. ClinicalTrials.gov identifier: NCT04459351. © RSNA, 2022 Online supplemental material is available for this article.

COVID-19 related concerns of people with long-term respiratory conditions: a qualitative study.

BACKGROUND: The COVID-19 pandemic is having profound psychological impacts on populations globally, with increasing levels of stress, anxiety, and depression being reported, especially in people with pre-existing medical conditions who appear to be particularly vulnerable. There are limited data on the specific concerns people have about COVID-19 and what these are based on. METHODS: The aim of this study was to identify and explore the concerns of people with long-term respiratory conditions in the UK regarding the impact of the COVID-19 pandemic and how these concerns were affecting them. We conducted a thematic analysis of free text responses to the question "What are your main concerns about getting coronavirus?", which was included in the British Lung Foundation/Asthma UK (BLF-AUK) partnership COVID-19 survey, conducted between the 1st and 8th of April 2020. This was during the 3rd week of the UK's initial 'social distancing measures' which included advice to stay at home and only go outside for specific limited reasons. RESULTS: 7039 responses were analysed, with respondents from a wide range of age groups (under 17 to over 80), gender, and all UK nations. Respondents reported having asthma (85%), COPD (9%), bronchiectasis (4%), interstitial lung disease (2%), or 'other' lung diseases (e.g. lung cancer) (1%). Four main themes were identified: (1) vulnerability to COVID-19; (2) anticipated experience of contracting COVID-19; (3) pervasive uncertainty; and (4) inadequate national response. CONCLUSIONS: The COVID-19 pandemic is having profound psychological impacts. The concerns we identified largely reflect contextual factors, as well as their subjective experience of the current situation. Hence, key approaches to reducing these concerns require changes to the reality of their situation, and are likely to include (1) helping people optimise their health, limit risk of infection, and access necessities; (2) minimising the negative experience of disease where possible, (3) providing up-to-date, accurate and consistent information, (4) improving the government and healthcare response.

Social isolation, loneliness and physical performance in older-adults: fixed effects analyses of a cohort study.

Isolation and loneliness are related to various aspects of health. Physical performance is a central component of health. However, its relationship with isolation and loneliness is not well understood. We therefore assessed the relationship between loneliness, different aspects of social isolation, and physical performance over time. 8,780 participants from the English Longitudinal Study of Ageing, assessed three times over 8 years of follow-up, were included. Measures included physical performance (Short Physical Performance Battery), loneliness (modified UCLA Loneliness Scale), and isolation considered in three ways (domestic isolation, social disengagement, low social contact). Fixed effects regression models were used to estimate the relationship between changes in these parameters. Missing data were imputed to account for variable response and ensure a representative sample. Loneliness, domestic isolation and social disengagement were longitudinally associated with poorer physical performance when accounting for both time-invariant and time-variant confounders (loneliness: coef = - 0.06, 95% CI - 0.09 to - 0.02; domestic isolation: coef = - 0.32, 95% CI - 0.46 to - 0.19; social disengagement: coef = - 0.10, 95% CI - 0.12 to - 0.07). Low social contact was not associated with physical performance. These findings suggest social participation and subjectively meaningful interpersonal interactions are related to physical performance, and highlight additional considerations regarding social distancing related to COVID-19 control measures.