I'm not very familiar with the situation in Nigeria, but my understanding is there's a lot of dust in the air much of the year from the Sahara, plus in Lagos and other cities there's a lot of pollution, is that right? In that case I wouldn't recommend UVC at all (since it inactivates pathogens but doesn't touch dust or pollution). Instead, something filter-based would have much broader benefits: dust and pollution in addition to pathogen control.

In the US the cheapest filter option is generally as Corsi-Rosenthal box (a box fan plus HVAC filters, both commodity items here). In Nigeria, something commercial would probably be cheaper since those aren't everyday items. Looking online a bit, maybe the Acerpure Pro P2 at ~₦120,000 for 191 CFM CADR is best? While that's a lot cheaper than the Aerolamp, though, that's still out of reach for someone at ₦70,000 / month.

(Minor: the Aerolamp also uses Care222)

Is this run by Aerolamp or someone else?

My external post probably would have been better with some explicit comparisons, but my claim is that in-duct UVC (a) isn't widely applicable, and so the overall potential benefit of pushing for it is low and (b) isn't cost effective even where it's applicable.

I think (b) is the more important one and where we most disagree. I've now added the cost-effectiveness calculation to the end of https://www.jefftk.com/p/against-in-duct-uv and it looks to me like even in the best case in-duct is much more expensive per CADR than filters or far-uvc.

Wrote this up as a full post: https://www.jefftk.com/p/against-in-duct-uv

vastly more effective, cost-efficient, and problem-free method of UV in ductwork (Near UV) gets pretty much zero attention

The big problem is that ducts are relatively rare, something like 10% globally. While ducts are common in the US, Canada, and Australia, they're rare elsewhere including Europe and Asia. [1]

You also need to tune your HVAC to recirculate a lot of air even when the system isn't calling for heat or cooling, which people usually don't.

And then if you do have ducts and are moving a lot of air you don't need UV: if you're running MERV-13 (typically the most the blower is able to handle) that's removing worst case 50% of particles, and you can generally put out enough air to hit targets with the existing system. And then consider that in-duct UV systems fail invisibly and fail open.

[1] Around here the old houses are mostly radiators, new ones are mostly mini-splits, and only ones built or renovated in between have ducts. Older commercial buildings are also generally radiators, though that's becoming less common. I asked Claude Opus 4.7, ChatGPT 5.5 Thinking, and Gemini 3.1 Pro "Approximately what fraction of indoor hours spent by humans around the world are in spaces with a ducted HVAC system? What's your 50% confidence interval?" and got 9-13%, 10-20%, and 6-11%. The big factor here is that while ducts are common in the US, Canada, and Australia, they're rare elsewhere including Europe and Asia.

Thanks for updating the post! Some minor comments:

the $500 row reflects the cheapest current Care222-based fixture, not the price of a productized, FCC- and UL-8802-certified consumer product.

Good point!  This is definitely an issue I've run into in talking to people about whether installing Aerolamps makes sense, and I was excited to learn they're working on a new version that should both cost less and be certified.

Jeff Kaufman's post reaches ~$53 per eACH for the Aerolamp using aerosol-k coronavirus susceptibility (Welch et al. (2022))

Not exactly: I used the median eACH value I got from Illuminate:

This gave me a median of 11.55 eACH, across 25 bacteria and viruses with a range from 0.442 to 44.06.

I also assume no replacement for the Aerolamp but use bench k

Why use bench-measured k?  Isn't that less realistic for real-world use?  This isn't something I know much about, though, and I'm just going with Illuminate's defaults.

I think you may also somewhat overestimate the CADR decline for these devices when not operating at full power

Certainly possible, and I'd be happy to yield to lab testing on this, but in my DIY testing turning a AP-1512 from "high" to "medium" dropped CADR by 50%, and this AirFanta review found going from 56 dB to 45 dB dropped CADR by 40%.

That seems much too strong to me: it's very important that AI companies have accurate views on how dangerous their models are. When AISI evaluated Mythos and confirmed its high level of cybersecurity ability, this (from the outside) looks critical to Anthropic deciding not to release it publicly yet. This likely reduced near term risk, set some precedent, and also slowed the race slightly.

(Disclosure: the other side of SecureBio does AI evals; speaking for myself)

However, not studying dentistry could also be a risk if human-level AGI comes slowly — for instance, if AGI isn’t developed in the next 30 years. In that case, dentists probably won’t be replaced for 30 years.

I think this is unlikely, since almost all work that is done by dentists today could be automated with current levels of AI. In theory this could mean more employment for dentists, since perhaps if dentistry were cheaper people would want a lot more of it, but while I do think this is how things work in many fields I think that's unlikely for dentists.

I think it's overall very hard to predict where things would go, so if I were a college freshman I would try to (a) maximize my options by staying flexible and learning a lot of different things and (b) stay on top of the tech as it matures so I'm in a position to notice when things newly become possible and take advantage of that (younger people tend to be much more adaptable).

This creates a credible commitment where the charity receives funds if and only if a matcher steps in. So the matcher can be confident that their donation actually caused the charity to receive the funder’s contribution.

It looks to me like you can't be confident that the matcher who steps in is someone other than the funder, and the funder being their own matcher-of-last-resort destroys the counterfactuality.

Let's say I intend to donate $2X to a charity. I use your system, with a pot of $X. If people donate $X, I send an additional $X to my charity some other way and it receives a total of $3X. If people donate $0 I anonymously use my second $X to meet the terms of the smart contract, and it receives a total of $2X (same as if I'd not set up this match). My $2X went to the charity regardless, and no one who contributed to the matching campaign affected the distribution of my funds.

@Ben Kuhn has a log at https://www.benkuhn.net/ea/ , though the last donation is 2019.  I don't know if that's putting giving on hold vs no longer updating the list?