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Aerosolisation and Transmission of SARS-Cov-2 in Healthcare Settings (AERATOR)
Florence Gregson, Sadiyah Sheikh, Fergus Hamilton, Mark Gormley, Jules Brown, Nick Maskell, Bryan R. Bzdek, JONATHAN P. REID, University of Bristol, U.K.
Abstract Number: 186
Working Group: Infectious Aerosols in the Age of COVID-19
Abstract
The transmission of respiratory diseases such as SARS-CoV-2 is known to occur through inhalation of aerosols or larger droplets containing respiratory secretions. Certain medical procedures, wherein high air flow travels over respiratory mucosa, are thought to generate viral aerosol and pose transmission risk to people in the vicinity when performed on infected patients. Through the study AERosolisation And Transmission Of SARS-CoV-2 in Healthcare Settings (AERATOR), we set out to quantify the aerosol generated during such procedures, classified as Aerosol Generating Procedures (AGPs). We cover a broad range of medical specialities, such as anaesthesia, orthopaedic and ophthalmic surgery, respiratory medicine and dentistry. Sampling the aerosol generated in real clinical procedures involves working around a series of environmental constraints, such as a high aerosol background concentration and positioning instrumentation as close to the source as possible around clinical staff. In all measurements we consistently sample aerosol with either an optical particle sizer (Dp = 0.3-10 µm) or Aerodynamic Particle sizer (0.5 – 20 µm) to measure both the aerosol concentration and the size distribution. However, we adapt our protocol for each clinical speciality for as reliable measurements as possible. Some studies, such as delivery of non-invasive ventilation (NIV) in respiratory medicine, involve healthy volunteers performing procedures in an ultra-clean background to unequivocally assign the sampled aerosol to the procedure. For dental procedures, plumes of aerosol are generated by the drills or ultrasonic scalers themselves, so we compare the modes within the generated size distribution from phantom controls with patient data. Our results suggest that patient coughing poses greater risk of aerosol generation than many NIV procedures (Hamilton et al, Lancet Resp. Med., 2021) and that policy of PPE, ventilation strategies and the use of patient facemasks in some medical procedures should be re-evaluated.