Thread by @masknerd

[1]Looking to the future of Far-UVC
Catherine Noakes, University of Leeds
@CathNoakes
#ICFUST
#ICFUST2023

[2]written in direct response to the conference (and during the conference) reminder: COVID has caused enormous caseload and death and pre COVID lower respiratory infection was already #4 cause of worldwide death.

[3] This is a huge health challenge worldwide
three vectors for air and infection: communicable diseases( TB measles, flu), opportunistic pathogens (aspergillusm, NTMs, etc), airborne role in other infections (mrsa, c diff, norovirus)

[4] This is part of a much bigger picture of air and building concerns. considerations include air pollution, building regulations, noise, security, comfort, cost of space, temp, drafts, environment vs other investments, sustainability

[5] In UK, royal academy of engineering investigated messaging, mitigation, and planning in response to pandemic. Including focus grouping and working grouping "infection resilient environment" guidelines
commissioned study of cost effectiveness of better (safer) air

[6] Examining ventilation: huge benefit in community buildings, also clear benefit in commercial benefit
Ok let's talk about the future and far-uv. does it work? is it safe?

[7] Many ways to understand far uv: lab studies, eye and skin studies, controlled experimental studies, modelling, and real world data. One place to focus this understanding is inactivation rates: on surfaces, in air,different container/surface/chamber, as designed and/or modeled

[8] Further needs in inactivation rate research: how do we compare between test rigs? assays? lamps? microorganisms? suspension fluids? aerosol sizes? temperature? humidity?what are the fundamental mechanism explaining different inactivation characteristics

[9] Time for room scale . closer to "real world" inactivation. Potential to look at lamp position ventilation, etc. Two ways to do it
Steady State: Measure what the long term rates of bacteria/virus
Decay Test: Measure short term changes, but hard to because of timing.

[10] Decay test for some EPA type tests, but also have to do control and measure natural decay rate.
Only two room experiments HK group and Leeds group

[11] Differences in inactivation?
Eadie et al. got 10x the expected rate? Why? Both tests using "normal" air show higher rates. Is that why? Not sure at the moment.

[12] Lots we don't know and complexities.
specialist biological facilities. Very limited data so far. some viruses are hard to work with and get to high enough concentration to measure.

[13] Modelling really hard too.
Ideal vs realistic, non-steady state conditions in real-life(people, doors, weather)
How do you merge it all, it's complex and how do you validate? Small scale chambers help close

[14] Complexity of Real People Breathing:
Everyone breathes different, different height, different conditions, particle sizes. Very complex and not currently captured to-date in any models.

[15] What do we need from the real world?
Bioburden as part of the cost benefit analysis. Characterizing robustness and maintenance needs of devices. UK primary school study, looking at HEPA filters and upper room UV in 30 primary schools.

[16] Outputs are illness, absence, IAQ,
evaluating effectiveness and practicality
results are unpublished but promising!

[17] Health risks vs health benefits:
Potential to reduce exposure to pathogens and infection which can break transmission chain, control hugely on populational level.
Application example: healthcare stay (patient)
-HAI happening a lot, short duration to IAQ minimal

[18]Staff
Shorter daily exposure but chronic
air chemistry could be significant if poorly ventilated, but COVID risk/infection risk is quite high.
Must consider the trade offs!

[19] Long COVID is part of this equation. Need to estimate by exposure, cost benefit, demographic, long term concerns. Bigger Picture: climate change has changed disease, building needs, air awareness

[20] All air cleaning has pros and cons.
HEPA filters are easy, safe, an grab microbes and particles, present issues of noise, space, removal,
upper room 254: safe, good inactivation, quiet. inappropriate in some spaces, some chemistry issues

[21] Ionization: quiet, slightly unknown, some chemistry concerns 222: unobtrusive, quiet, effective, need more efficacy/chemistry examination
must think about this in the context of optimized applications.

[22] 222 presents the opportunity for major reduction is exposures/case numbers without increased energy costs, etc. Are we ready to produce guidance? unsure, but we are ready to say more about it, more publicly
more data needed for size concerns, implementation, installation