Fair argument, but let’s not forget that indoor air quality, HEPA filters, and upper air UV systems weren’t even allowed to be discussed as solutions to airborne transmission of viruses not that long ago. It was all about masks/no masks, remember? It’s a little unfair to say that things haven’t been studied, when it would have been career damaging to do so until very recently.

This is baloney? Air quality experts like Richard Corsi (UC Davis, now, poor guy, the dean of the college of engineering) have been advocating for increasing both external ACH (air changes/hour) and filtration ACH since nearly the beginning of the pandemic.

> Early in the pandemic, his efforts focused on lowering inhalation dose of virus-laden aerosol particles indoors. He led an effort to develop an educational tool for assessing parallel interventions for lowering inhalation dose for aerosols and risk of infection in buildings. His concept of a low-cost and effective do-it-yourself air cleaner to combat virus-laden aerosol particles and wildfire smoke has become known worldwide as the Corsi-Rosenthal Box. He recently chaired a National Academies committee responsible for the 2024 report, “Health Risks of Indoor Exposure to Fine Particulate Matter and Practical Mitigation Solutions.”

An awful lot of people who pay attention to engineering solutions for airborne risk reduction - the people who know what ASHRAE is - were saying exactly the same thing throughout nearly the entirety of the pandemic. Because of their advocacy and data, as one example, we got HEPA filters installed in our kids' elementary and preschools as part of the strategy to resume in-person education.

Got a source? I don't remember anyone objecting to studying HEPA filters' impact on airborne viruses. In fact, I've found studies on that exact topic from that time period. The CDC was saying that HEPA combined with masks was more effective than masking alone back in 2021 (but masking alone was better than HEPA alone)

> Without the HEPA air cleaners, universal masking reduced the combined mean aerosol concentration by 72%. The combination of the two HEPA air cleaners and universal masking reduced overall exposure by up to 90%. The HEPA air cleaners were most effective when they were close to the aerosol source

  2022: https://pubmed.ncbi.nlm.nih.gov/35947419/
  2022: https://pubmed.ncbi.nlm.nih.gov/34098798/
  2021: https://www.cdc.gov/mmwr/volumes/70/wr/mm7027e1.htm

Yep, I agree. Other comments here seem to display a collective amnesia but there was very clearly a mandatory authoritarian single solution to COVID and alternatives were not allowed to be considered even if they were good substitutes. Bringing up alternatives would get you censored or banned or just attacked.

Karolinska Institute in Sweden did a study during the pandemic that had findings of virus particles in every location in the hospital ventilation system, past all filters and air purifying. It was a early finding that indicated the role of recycled air in spreading the virus in places like airports, planes, trains and large buildings like shopping malls. The covid virus is so small and so effective as a airborne virus that even hospital filters had a limited effect.

> It was all about masks/no masks, remember?

No I don't. What I remember is that they said a lot about social distancing and going outside, and for those who do have to be around others, they initially said you gotta wear N95 since ordinary masks aren't very effective, then they said there's a shortage of N95 masks so please just wear normal masks since at least it's better than nothing, and save the N95s for the hospitals and other high-risk settings/workers.

If you remember it differently, please explain what I'm misremembering, because (unlike a sizable fraction of the population) I don't remember hearing anything nonsensical or misleading about masks, especially given the information and resources they had available at the time.

No, I do not remember that. I'm pretty sure you just made it up. Air filtering is obviously long-studied, and if you are alluding to COVID-era events I seem to recall that one of the first large-scale responses that happened in my region was the subway operator installed up-rated HEPA+UV air cleaners on every car.

If you want to sustain this claim, show us the process by which someone's career was truncated by researching air filtration.

> It was all about masks/no masks, remember?

Every jurisdiction had an overreaction fetish. Masks, social distancing and vaccine cards on the left. Ivermectin, detergent pods and intentional exposure on the right.

Maybe there was one with an anti-air filter message. But between New York, the Bay Area, Arizona, Tennessee, Wyoming, London, Frankfurt and New Delhi, I didn’t see it.

> It was all about masks/no masks, remember?

You're clearly pushing an agenda. The problem is that these kind of filtration systems couldn't be rolled out en-masse across the world.

During COVID hospitals absolutely were using air filtration systems and places where it made sense (I remember COVID doctor's conferences had advanced filters for each room).