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Are aerosols generated during lung function testing in patients and healthy volunteers? Results from the AERATOR study
  1. Sadiyah Sheikh1,
  2. Fergus W Hamilton2,3,4,
  3. George W Nava5,
  4. Florence K A Gregson1,
  5. David T Arnold5,
  6. Colleen Riley6,
  7. Jules Brown7,
  8. AERATOR Group,
  9. Jonathan P Reid1,
  10. Bryan R Bzdek1,
  11. Nicholas A Maskell8,9,
  12. James William Dodd10
    1. 1Bristol Aerosol Research Centre, School of Chemistry, University of Bristol, Bristol, UK
    2. 2Department of Infection Science, North Bristol NHS Trust, Bristol, UK
    3. 3Population Health Sciences, University of Bristol, Bristol, UK
    4. 4MRC Integrative Epidemiology Unit, Bristol, UK
    5. 5Academic Respiratory Unit, University of Bristol, Bristol, UK
    6. 6Respiratory Physiology, North Bristol NHS Trust, Westbury on Trym, UK
    7. 7Anaesthetics and Intensive Care Department, North Bristol NHS Trust, Westbury on Trym, UK
    8. 8North Bristol Lung Centre, Southmead Hospital, Bristol, UK
    9. 9Academic Respiratory Unit, Department of Clinical Sciences, Bristol University, Bristol, UK
    10. 10Academic Respiratory Unit, North Bristol NHS Trust, Westbury on Trym, UK
    1. Correspondence to Dr Fergus W Hamilton, Department of Infection Science, North Bristol NHS Trust, Bristol BS10 5NB, UK; gushamilton{at}gmail.com

    Abstract

    Pulmonary function tests are fundamental to the diagnosis and monitoring of respiratory diseases. There is uncertainty around whether potentially infectious aerosols are produced during testing and there are limited data on mitigation strategies to reduce risk to staff. Healthy volunteers and patients with lung disease underwent standardised spirometry, peak flow and FENO assessments. Aerosol number concentration was sampled using an aerodynamic particle sizer and an optical particle sizer. Measured aerosol concentrations were compared with breathing, speaking and voluntary coughing. Mitigation strategies included a standard viral filter and a full-face mask normally used for exercise testing (to mitigate induced coughing). 147 measures were collected from 33 healthy volunteers and 10 patients with lung disease. The aerosol number concentration was highest in coughs (1.45–1.61 particles/cm3), followed by unfiltered peak flow (0.37–0.76 particles/cm3). Addition of a viral filter to peak flow reduced aerosol emission by a factor of 10 without affecting the results. On average, coughs produced 22 times more aerosols than standard spirometry (with filter) in patients and 56 times more aerosols in healthy volunteers. FENO measurement produced negligible aerosols. Cardiopulmonary exercise test (CPET) masks reduced aerosol emission when breathing, speaking and coughing significantly. Lung function testing produces less aerosols than voluntary coughing. CPET masks may be used to reduce aerosol emission from induced coughing. Standard viral filters are sufficiently effective to allow guidelines to remove lung function testing from the list of aerosol-generating procedures.

    • infection control
    • respiratory infection
    • respiratory measurement

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    Footnotes

    • Twitter @gushamilton, @theotherdodd

    • NAM and JWD contributed equally.

    • Collaborators The AERATOR group consists of (in alphabetical order) Arnold D, Brown J, Bzdek BR, Cook T, Davidson A, Dodd JW, Gormley M, Gregson F, Hamilton F, Maskell N, Morley A, Murray J, Keller J, Pickering AE, Reid J, Sheikh S, Shrimpton A and White C.

    • Contributors JWD, NAM, FWH, SS, FKAG, DTA, GWN and JB designed the experiments. CR performed the lung physiology testing. SS and FKAG analysed the data, with BRB and JPR providing supervisory support and analysis. GWN performed supplementary experiments.

    • Funding This study was funded by the UKRI-NIHR Rapid COVID-19 Call (COV003). FWH’s time was funded by the GW4-Wellcome Doctoral Fellowship Scheme. JWD’s time was funded by an MRC CARP Fellowship (MR/T005114/1). BRB acknowledges support from the Natural Environment Research Council through Grant NE/P018459/1.

    • Competing interests None declared.

    • Provenance and peer review Not commissioned; externally peer reviewed.

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