Hi Sanjay, thanks for the comment!

sounds like a pretty great cherry on the cake

Indeed, I think part of the path to impact for far-UVC will be that adoption will hopefully be driven by, e.g., employers like Google equipping their offices with far-UVC lamps because they expect this to reduce the total number of sick days of their workers and therefore increase productivity + profits. Getting this type of evidence for efficacy would be great since it would be an excellent sales pitch to companies whose employees earn a lot, meaning sick days are costly. Ideally, you would be able to tell them something like, "Installing these far-UVC fixtures in the whole office will cost you $30,000, but based on existing evidence and our best models, you'll likely recoup those costs after approx. 18 months due to a reduction in sick days of your employees." 

Presumably, that would be a big boost for demand and competition, thereby reducing costs and increasing R&D. It could help to make far-UVC widespread enough to make a difference in stopping future outbreaks or slow down the spread of disease during the next pandemic. 

but could it exacerbate pandemic risk by reducing immunity, thereby making it easier for a bioweapon engineer to create a scary pathogen?

There has been very little research on the interaction of far-UVC and the immune system. It is a topic that often comes up in discussions around far-UVC safety and is related to the well-known "hygiene hypothesis," which says something like, "If you're not exposed to enough germs as a child, you might get more allergies." 

I want to see more research on this, but so far, it hasn't been as much of a priority. First, people wanted to figure out things like whether far-UVC could give you skin cancer or make you blind. By now, we know those things won't happen, so we can turn to more "second-order" type risks like immune system effects. 

However, I have a few intuitions about why this seems unlikely. First of all, it is an "end-game" worry in the sense that it seems like it would only become relevant once far-UVC is almost ubiquitous. Even if it becomes widespread, it would be installed in places like hospitals, shared offices, public transport, etc., but you probably wouldn't have it in your home or anywhere outside. Let's say you would spend ~10 h per day in environments that have much more sterile air than nowadays, but the other ~14 h, you're at home or wherever and still exposed to the germs of, e.g., your partner or children.  

Also, I expect that even widespread far-UVC wouldn't reduce fomite transmission much because its disinfection works by line of sight and is easily shielded. So your immune system would still be challenged by that type of transmission.

As I wrote in the post, we only really care about far-UVC if we can find a path to really widespread adoption and high enough doses to slow down or even stop the transmission of extremely infectious agents like measles. If we actually achieve pathogen suppression that strong, I find it hard to imagine a malevolent actor engineering a pathogen so scary that it overwhelms this system. Remember that far-UVC would only be one of our defenses against pandemics and would be combined with PPE, ventilation, medical countermeasures, etc.  

I also haven't seen any convincing evidence that a reduction in your exposure to germs dramatically worsens your immune system. While I haven't looked into it deeply, the hygiene hypothesis seems to be somewhat controversial and concerns things like allergies, not, e.g., doubling your susceptibility to common infections because of a worse immune system. 

Similarly, I have heard claims that due to all the social isolation, masking, etc., during the Covid pandemic, peoples' immune systems got worse. Yes, the flu + RSV season peaked earlier last winter and was decently bad, but I don't see how this can be attributed to a broad decrease in immune competency. Rather, it just seems like many people weren't exposed to these specific pathogens that they would have typically been challenged with more frequently. I'm not terribly knowledgeable here, so might be mistaken, would be curious if other folks have more insights.

I agree. Getting more data on risks (safety) and real-world efficacy to formulate a more comprehensive and convincing cost-benefit calculus is probably the biggest priority for far-UVC right now.

This is the hottest topic in the far-UVC field right now. There were also a bunch of talks about it at the recent ICFUST conference. You can watch recordings of those talks here.

Also, see this helpful list of existing studies around far-UVC and indoor air chemistry: http://bit.ly/guv-chem

While I haven't read all of the studies in detail, my impression is that some of the results seem to disagree with each other, and the issue isn't settled yet. 

Some thoughts from a draft for a forum post I wrote:

• Undoubtedly, far-UVC has a substantial impact on indoor air chemistry by producing ozone, which oxidizes volatile organic compounds in the air that can result in harmful products such as particulate matter
  • The debate surrounds the question of how detrimental this is and existing studies seem to disagree somewhat to what extent this is a substantial issue.
  • Importantly, little research has been done on methods to mitigate this issue! 
    • For example, using activated carbon filters to remove ozone, making sure far-UVC is used with sufficient ventilation to remove ozone, or altering far-UVC fixture designs. 

Maybe helpful context: Using germicidal UV-C has always been a risk-benefit calculus. With far-UVC, the tradeoff might be chemical vs. biological, while with conventional upper-room GUV it was probably physical (eye-irritation) vs. biological. 

Awesome! I have been wanting something like this for a while and am looking forward to trying it out.

See this previous comment of mine for some potentially interesting suggestions:

https://forum.effectivealtruism.org/posts/cbtoajkfeXqJAzhRi/metaculus-year-in-review-2022?commentId=dotzeW2wxM5Avm7jL

(Excuse formatting; on mobile)

Just pointing out quickly that this was also posted on Lesswrong and that there are 39 comments with additional discussion over there (as of July 2023).

I would recommend just shooting them an email :)

http://sandhoefner.github.io/animal_suffering_calculator

This tool is similar. I think I have seen another very similar one, but I might be confusing them.

Yea, that could be the case, although I assume having Elon Musk sign could have generated 2x the publicity. Most news outlets seem to jump on everything he does. 

Not sure what the tradeoff between attention and controversy is for such a statement. 

I'm mildly surprised that Elon Musk hasn't signed, given that he did sign the FLI 6-month pause open letter and has been vocal about being worried about AI x-risk for years.

Probably the simplest explanation for this is that the organizers of this statement haven't been able to reach him, or he just hasn't had time yet (although he should have heard about it by now?). 

The Overedge catalog looks extremely interesting. Thanks!