Stand-alone air decontamination units: some questions…

I’ve been involved recently in a comparative evaluation of several stand-alone air decontamination units. Please feel free to take a look at our (very!) preliminary findings here. I also attended the HIS Spring Meeting today, which was all about ventilation in healthcare settings. Whilst I found the day interesting and thought provoking, I’ve left with more questions than I had before!

Here’s why I think it’s a good time to be looking closely at stand-alone air decontamination options:

  • Contaminated air can be a vector for the transmission of key hospital pathogens, including respiratory viruses such as SARS-CoV-2.
  • Ventilation in healthcare buildings frequently falls below minimum standards.
  • Key pathogens can be identified in hospital air, in a range of particle sizes (e.g. Influenza, MERS, and SARS (including SARS-CoV-2)).
  • Also, pathogens not traditionally associated with contamination of the air can be found in the air (e.g. C. difficile, Acinetobacter and MRSA).3-4
  • Air decontamination systems can substantially – and rather impressively – reduce the levels of pathogenic micro-organisms in hospital room air.
  • The latest UK hospital guidance for SARS-CoV-2 and other respiratory viruses includes a recommendation to consider alternative technologies to improve air hygiene when ventilation is considered inadequate or cannot be assessed.

Here’s my key questions:

  • Which technological approach do we take? There are units that use HEPA only, HEPA+UV; there’s units that emit chemicals or certain wavelengths of light; there systems we can add to conventional ventilation setups. And more.
  • And what standards do we use to assess them? (It’s a bit of a standard-free-zone currently!)
  • How do we analyse and interpret engineering data (e.g. particle count, airflow) in the context of HCAI risk?
  • How quiet is quiet enough? And what would patients think of this approach?
  • Does it matter if smoke isn’t removed from every corner of the room? (I think probably not – we’re not trying to create a perfect ventilation system with these stand-alone units – but to mitigate risk where ventilation is considered inadequate.)
  • How do we get engineering specialists and infection specialists to speak the same language?
  • How many stand-alone units do you need to meaningfully improve air hygiene? And how does this change in larger and irregularly sized spaces? (Because we all have completely uniform single rooms and bays, right?)
  • How much of a factor is cost (unit price varies from hundreds to many thousands of pounds)?
  • Which is more important – background ventilation or stand-alone unit performance?

These are just some of the questions in my mind! This feels like an exciting area in which carefully planned applied research, in collaboration with engineering experts, can make a real difference.

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