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by Llamamoe 246 days ago
There's more to air quality than HEPA filters. In-line far UV sterilisation, ventilation to reduce rebreathing and CO2 levels, and HEPA might not be enough as a single-building intervention, but it would almost definitely change disease spread dynamics if deployed world/nation wide.
1 comments

> There's more to air quality than HEPA filters.

Agreed. In fact, even before COVID this was long overdue to be addressed in classrooms etc:

> ventilation to reduce rebreathing and CO2 levels

Unfortunately since that hasn't happened yet, methods like:

> In-line far UV sterilisation

> HEPA

are not effective. It isn't that they don't kill/stop the virus. The problem traces back to the inadequate forced air exchange and distribution which these methods require, and which is often a show stopper when you're talking about retrofitting existing structures without costs becoming insane. At a certain point it's easier to build new with these things in mind (and we absolutely should be taking requirements to do so more seriously).

> might not be enough as a single-building intervention, but it would almost definitely change disease spread dynamics if deployed world/nation wide.

The point of the previously linked study is to demonstrate that "something is better than nothing" reasoning doesn't always apply. We need to go big to see an actual measurable improvement over longer time spans. Otherwise, what's the benefit seen if you delay an average (but inevitable) infection from occurring by X days? There basically is none.

> Otherwise, what's the benefit seen if you delay an average (but inevitable) infection from occurring by X days? There basically is none.

It reduces the R0 factor, which reduces the amount of people that need to be resistant for herd immunity to take place, and which makes it easier for other measures to bring it down further, potentially below 1 where the disease dies out instead of continuing to spread.

> It reduces the R0 factor

The results of the study suggest it doesn't, as measured by outcomes:

> While we did not find an association between HEPA purifier use and high overall viral exposure, the intervention was associated with a 32.8% reduction in viral diversity. However, the clinical significance of these changes is not clear given that we did not find an association between viral diversity and school absenteeism.

Point being, it only takes a very small dose of a aerosol borne virus to keep it in circulation. Breaking this chain requires extreme measures. Not impossible to achieve, but not trivial, either. Considering the widespread damage that long COVID is causing, I sincerely hope we find a way.