Method for controlling SARS-CoV-2 containing aerosols by C D Mayes. Dept. Nuclear Medicine, Royal Liverpool University Hospital, Liverpool, UK

The CoVid-19 pandemic has highlighted the need for good scientific understanding and control of airborne infections. In October 2020 the US National Academy of Sciences, Engineering and Medicine (NASEM) held a workshop on ‘The Airborne Transmission of SARS-CoV-2’. The proceedings of this meeting have been published and are available as a free to download document¹ which gives an useful and up to date overview. Much interest has been shown by the medical professions in the possibility of aerosol transmission of CoVid-19 and this document discusses the state of the art of this subject. Common misconceptions on the nature of droplets and aerosol particles were explored and current understanding outlined. Control methods to prevent transmission were discussed including the effectiveness of behavioural change, mask wearing, ventilation and filtration techniques.

The whole document is recommended as a useful introduction to the subject for any healthcare scientist. The examination of air filtration technology is particularly interesting to colleagues who are involved in Nuclear Medicine departments where inhaled vapours of ultrafine radioactive aerosol particles such as Tc^99m labelled Technegas have been used for many years in clinical ventilation/perfusion lung scans for patients suspected of Pulmonary Embolus. One method for safely sequestering any potential radioactive contamination released during this technique is to use an Ultra Low Particulate Air (ULPA) filtration system. ULPA filters are high specification versions of the well known HEPA systems that are used to provide filtered air (in laminar air-flow cabinets for example) and these are discussed in the NASEM document. Mayes² has recently published a scientific paper on the clinical effectiveness of using a mobile ULPA filtration system as a control measure during patient inhalation of radioactive vapours. He suggested that these may also be useful against exhaled droplet and aerosol particles that may contain viruses such as SARS-CoV-2.

Scientific professionals other than those in Nuclear Medicine have concerns about aerosol generating procedures (AGPs). They may well find this approach to air-flow filtration worth exploring as an additional infection control measure in their own clinical practice during the present pandemic.

References.

1. https://www.nap.edu/catalog/25958/airborne-transmission-of-sars-cov-2-proceedings-of-a-workshop?utm_source=NASEM+News+and+Publications&utm_campaign=a4c35901dd-NAP_mail_new_2020_10_26&utm_medium=email&utm_term=0_96101de015-a4c35901dd-111013786&goal=0_96101de015-a4c35901dd-111013786&mc_cid=a4c35901dd&mc_eid=74d4081509
2. Safe practice ventilation technique in lung scanning for pulmonary embolism Mayes, Christopher Duncan
   Nuclear Medicine Communications. 41(12):1328-1333, December 2020.