- A lot of the analysis on this misses the mark: • “They weren’t on” — maybe, but filtration data says otherwise • “Too small / not ASHRAE 241” — data disagrees. And none of it actually says anything about transmission of respiratory illnesses. 🧵1/n
- HEPA purifiers not tied to less #viral exposure in elementary classrooms, analysis finds #HEPA purifiers were associated with a 33% decrease in viral diversity, but the reduction wasn't linked to fewer school absences. www.cidrap.umn.edu/i...
- First of all this was an initial study into the impact of HEPA purifiers with and without filters on childhood asthma undertaken between 2015-2020. The primary results of that are elsewhere (tldr HEPA had no impact on asthma incidence) jamanetwork.com/journals/jam... 2/n
- at the same time they collected air samples from these classrooms and have analysed these samples recently to assess how much and how many pathogen genomic material are present in the air with and without HEPA 3/n
- The results show an interesting spread of viruses that change in prevalence over the year (note there is no SARS-CoV-2 bcos this predates the pandemic, plenty of other coronaviruses tho) 4/n
- This is super interesting - do you know how much it costs to get a dataset like this? I'm wondering if it would be viable for community surveillance.Oct 15, 2025 20:02
- Air sampled for a week, frozen and analysed several years later. Some kind of preamplification then quantitative PCR. I imagine the most cost will be setting up air sample and collection.
