The Investigation of Particulate Respiratory Matter to Inform Guidance for the Safe Distancing of Performers in a COVID-19 Pandemic (PERFORM-2)

Lead Research Organisation: University of Bristol
Department Name: Chemistry

Abstract

Respiratory particles emitted during human exhalatory events by an individual infected with SARS-CoV-2 are known to span a wide size range, from large macroscopic droplets to small aerosol particles. Although these droplets (>5 micrometres diameter) and aerosols (<5 micrometres) are responsible for direct, indirect and airborne modes of viral transmission, the concentrations and fluxes expired during activities such as speaking, singing, playing musical instruments and exercising, are poorly quantified and, in some cases, remain completely unknown. An absence of data, essential to inform assessments of risk in restarting activities, has led to precautionary measures that severely restrict singing, musical performance and sport, across both the amateur and professional domains. Building on preliminary work with a cohort of professional musicians, we will provide a comprehensive analysis of aerosol and droplet emissions from singers covering a broad range of genres, as well as woodwind and brass instruments. Working in an orthopaedic operating theatre, an environment of "zero aerosol" background, we will extend our study to quantify respirable particles exhaled by amateur musicians and individuals undertaking exercise, explore rigorously the distance of large droplet transmission and aerosol flux, focusing on super-emitters, and work with speech and language therapists to understand the risks of aerosol generating procedures used during therapy. In a range of venue types (from a modern auditorium to an historic church), we will measure the dynamics of aerosol dispersion and clearance, informing computational fluid dynamics models of aerosol spread and assessments of exposure risk.
 
Description The project has 7 work-packages (WPs) progressing in parallel. In more detail, commensurate with the workplan, progress has been made on the following aspects of the project.

WP1 - PERFORM-1 Analysis: We have completed analysis of the aerosol measurements from wind instruments undertaken in PERFORM-1. This work has now been published in the journal Aerosol Science & Technology (DOI: 10.1080/02786826.2021.1947470).

WP2 - Cohort PERFORM-1 Extended: Our intensive, measuring aerosols emitted by professional singers and instrumentalists returning from PERFORM-1 was completed. Measurements have also been made with cohorts of flautists, clarinets and trumpet players to further explore the risks associated with playing wind instruments.

WP3 - The coronavirus disease-19 (COVID-19) pandemic has profoundly impacted sports and exercise. Airborne and droplet routes are important for transmission of SARS-CoV-2, with systematic evaluation of the release of aerosols and droplets during exercise required to assess risk. Healthy participants (n=25) performed an exercise test (CPET) on a cycle ergometer to replicate vigorous and high intensity exercise. Concurrent aerosol and ventilatory measurements were recorded. Median aerodynamic mass concentration during speaking was greater than during vigorous exercise, but not different to high intensity exercise. Aerosol size distributions recorded at rest and during exercise were similar; speaking emitted an additional mode at larger size 2-3µm. Median mass emission rate produced by speaking was not different to vigorous exercise but was lower than high intensity exercise. The size distribution of airborne particles emitted during exercise is consistent with that of breathing at rest, with increased minute ventilation the primary driver of the increased aerosol mass emissions rate that occur during exertion. Aerosol mass emission rates during vigorous exercise are not different to speaking at a conversational to loud-conversational volume. These findings enhance our understanding of particle release during exercise, enabling appropriate mitigations for airborne pathogens, including SARS-CoV-2.

WP4 - Aerosol particles of respirable are exhaled when individuals breath, 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 emission rates, as a route to provide estimates of viral shedding and the potential risk of transmission. We provide a robust assessment of the absolute particle number and mass emission rates from measurements of minute ventilation using CPET along with measurements of the exhaled particle number concentrations and size distributions. Specifically, we report comparisons of the number and mass emission rates for children (12-14 years old) and adults when breathing, speaking and singing, which indicate that children and adult cohorts generate similar amounts of aerosol when performing the same activity, but that vocalisation generates significantly more aerosol than breathing for both cohorts. Mass emission rates are typically 0.002 - 0.02 ng/s from breathing, 0.07 - 0.2 ng/s from speaking (at 70-80 dBA) and 0.1 - 0.7 ng/s from singing (at 70-80 dBA). The exhaled aerosol emission rate increases with increasing sound volume for both children and adults when both speaking and singing.

WP5 - Speech and Language Therapy: Measurements have been completed with a cohort of 24 participants. Data are being analysed and prepared for publication.

WP6 - Dispersion Measurements: A network of low-cost sensors is operational and measurements are complete of aerosol transmission and dispersal in a teaching room, used to benchmark WP7, supported by measurements of room ventilatory parameters such as flow velocities.

WP7 - CFD Modelling: ARUP have constructed a CFD model of the teaching room in WP6 and have validated their simulations by comparison with the data from WP6.
Exploitation Route The manuscripts published or prepared for submission on aerosol generation from wind instruments, singers, exercise, children performers and individuals undertakings peech and language therapy have been or are will soon be submitted to UK HSA and the UK government Department for Digital, Culture, Media and Sport for review of guidelines on the performing arts as we move out of the latest lockdown.
Sectors Government, Democracy and Justice,Culture, Heritage, Museums and Collections
 
Title Initial Phase of Pre-Work on PERFORM-2 Prior to Human Participant Study 
Description The project started in January 2021 and it is early stages to report progress. However, in line with the project objectives, we have: - Submitted a manuscript on aerosol generation from wind instruments for peer review and publication. - Initiated measurements of dispersion of aerosols in an indoor context using a network of low cost sensors. - Engaged ARUP as a sub-contractor to undertake the dispersion CFD modelling. - Secured ethical approval for the human participant studies which will start in late March 2021. 
Type Of Material Improvements to research infrastructure 
Year Produced 2021 
Provided To Others? No  
Impact Manuscript has been submitted to PHE and the UK government DCMS for review of guidance and policy on the performing arts. 
 
Description Collaboration with a team of medical practitioners and researchers 
Organisation Chelsea and Westminster Hospital
Country United Kingdom 
Sector Hospitals 
PI Contribution We have collaborated to deliver the PERFORM-2 project measuring aerosol emission rates from human participants.
Collaborator Contribution Support for measurements, analysis, manuscript writing, preparation of ethics application, recruitment of human participants
Impact Multiple publications are already published or in preparation from this work. Multidisciplinary collaboration involving medics from respiratory specialisms working with aerosol physicists and chemical physicists.
Start Year 2021
 
Description Collaboration with a team of medical practitioners and researchers 
Organisation Fortius Clinic
Country United Kingdom 
Sector Hospitals 
PI Contribution We have collaborated to deliver the PERFORM-2 project measuring aerosol emission rates from human participants.
Collaborator Contribution Support for measurements, analysis, manuscript writing, preparation of ethics application, recruitment of human participants
Impact Multiple publications are already published or in preparation from this work. Multidisciplinary collaboration involving medics from respiratory specialisms working with aerosol physicists and chemical physicists.
Start Year 2021
 
Description Collaboration with a team of medical practitioners and researchers 
Organisation Guy's and St Thomas' NHS Foundation Trust
Country United Kingdom 
Sector Public 
PI Contribution We have collaborated to deliver the PERFORM-2 project measuring aerosol emission rates from human participants.
Collaborator Contribution Support for measurements, analysis, manuscript writing, preparation of ethics application, recruitment of human participants
Impact Multiple publications are already published or in preparation from this work. Multidisciplinary collaboration involving medics from respiratory specialisms working with aerosol physicists and chemical physicists.
Start Year 2021
 
Description Collaboration with a team of medical practitioners and researchers 
Organisation Imperial College London
Department National Heart & Lung Institute (NHLI)
Country United Kingdom 
Sector Academic/University 
PI Contribution We have collaborated to deliver the PERFORM-2 project measuring aerosol emission rates from human participants.
Collaborator Contribution Support for measurements, analysis, manuscript writing, preparation of ethics application, recruitment of human participants
Impact Multiple publications are already published or in preparation from this work. Multidisciplinary collaboration involving medics from respiratory specialisms working with aerosol physicists and chemical physicists.
Start Year 2021
 
Description Collaboration with a team of medical practitioners and researchers 
Organisation Royal Brompton Hospital
Country United Kingdom 
Sector Hospitals 
PI Contribution We have collaborated to deliver the PERFORM-2 project measuring aerosol emission rates from human participants.
Collaborator Contribution Support for measurements, analysis, manuscript writing, preparation of ethics application, recruitment of human participants
Impact Multiple publications are already published or in preparation from this work. Multidisciplinary collaboration involving medics from respiratory specialisms working with aerosol physicists and chemical physicists.
Start Year 2021
 
Description Collaboration with a team of medical practitioners and researchers 
Organisation Wexham Park Hospital
Country United Kingdom 
Sector Hospitals 
PI Contribution We have collaborated to deliver the PERFORM-2 project measuring aerosol emission rates from human participants.
Collaborator Contribution Support for measurements, analysis, manuscript writing, preparation of ethics application, recruitment of human participants
Impact Multiple publications are already published or in preparation from this work. Multidisciplinary collaboration involving medics from respiratory specialisms working with aerosol physicists and chemical physicists.
Start Year 2021
 
Description Contribution to Royal Institution Christmas Lectures 
Form Of Engagement Activity A broadcast e.g. TV/radio/film/podcast (other than news/press)
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Public/other audiences
Results and Impact Prof. Jonathan Reid contributes to the 2021 Royal Institution Christmas Lectures, broadcast by the BBC. In lecture 2, The Perfect Storm, Jonathan shows how much aerosol we exhale when we breathe or vocalise, potentially transmitting viruses such as SARS-CoV-2.
Year(s) Of Engagement Activity 2021