2025-11-14 21:00:00
When the next pandemic hits, our ability to stop it will depend on the infrastructure we already have in place. A key missing piece is clean indoor air. An airborne pathogen can be very hard to contain, and we would want to move fast to limit spread. But how quickly we can get measures in place, and how thoroughly they would work, depends critically on the base we have to build up from.
Indoor air today is dirty by default. The air you breathe in is air others have breathed out, complete with a wide range of viruses and bacteria. It's a little gross if you think about it, and people do get sick a lot, but most of the time we just accept the downsides.
If something really serious were going around, though, this isn't a risk we'd accept. We'd need clean air: some combination of replacing infected air with outside air (ventilation), physically removing pathogens (purifiers, masks), or inactivating pathogens (far-UVC, glycol vapors).
I hear a lot about stockpiling as a way to set us up for clean air when we most need it. Get a lot of masks, air purifiers, far-UVC lamps etc ready to go, so they can be distributed in an emergency. I do think this helps, but there are serious limits:
What we need is regular ("peacetime") deployment. If a significant fraction (10%?) of rooms already had air purifiers, far-UVC, or other good options, not only would some need already be covered, but all the factors I just listed above work in your favor. You'd have the manufacturing capacity, the experienced installers, the good cheap products, and the public familiarity.
Key to peacetime deployment is peacetime benefits. You're not going to get to 10% of indoor spaces on the threat of a future pandemic. But millions of people die from airborne disease every year, people miss school and work, and being sick is just unpleasant. Cleaner air lets us make progress on all of these. While I'm coming at this from a biosecurity angle, the public health and economic benefits are also substantial.
I especially think it would be valuable to have more quantification here. If I'm an employer, how much will my company healthcare costs and sick days decrease if I deploy effective air cleaning? If I'm a superintendent in a district where I lose $50 each day each student is absent, how long before a given air cleaning system would pay for itself?
More demonstration would also be valuable, especially if the effects are as large as I expect them to be when you cover a large portion of someone's weekly exposure. If kindergartens with clean air have ~half the absenteeism they used to, that would be such a clear effect that people could see it in their own experience. You wouldn't need to present complicated statistics and discuss randomization approaches if the benefits were staring us in the face. I could point to the experience of Germantown Friends School in the 1937, but we need examples that aren't 88 years old.
It's counterintuitive to advance biosecurity by focusing on everyday public health, but it pencils out. We clean drinking water all the time, not just in response to cholera outbreaks. To have clean air in emergencies, figure out how to have clean air every day.
Comment via: facebook, lesswrong, the EA Forum, mastodon, bluesky
2025-11-12 21:00:00
I wanted to link an explanation of how
far-UVC works, why you might want to
use it to clean indoor air, and what we know about its safety. I
didn't find anything I liked, so I made something:
faruvc.org.
Let me know if you have ideas for making it better! My goal is to have something anyone can understand, without simplifying so much that it's misleading.
At some point I'd like to include an illustration showing far-UVC in use in an occupied space, but I don't have one I like right now.
(While I'm an employee of SecureBio, this is a personal project.)
2025-10-26 21:00:00
Per the Atlantic's A 'Death Train' is Haunting South Florida:
According to Federal Railroad Administration data, the Brightline has been involved in at least 185 fatalities, 148 of which were believed not to be suicides, since it began operating, in December 2017. Last year, the train hit and killed 41 people—none of whom, as best as authorities could determine, was attempting to harm themselves. By comparison, the Long Island Rail Road, the busiest commuter line in the country, hit and killed six people last year while running 947 trains a day. Brightline was running 32.
Trains running people over is obviously bad, but people also die from being hit by cars. Reading the article I was wondering: are we making a big deal about Brightline because it's big and new, but actually we're better off overall now that there's a train because fewer people are driving and so fewer people are dying? And is this actually counterproductive fearmongering? Nope! Brightline is just really deadly, not just for a train, but even relative to driving.
While Brightline is of course much safer for occupants than driving, what I care about is the overall social impact: are there more or fewer deaths than in a non-Brightline world? This means counting everyone, including occupants, drivers, and pedestrians. Ideally we would compare fatality rates directly: how many deaths are there per passenger-mile for Brightline vs cars? These stats don't exist, but we can get decent estimates:
For Brightline, per the article there have been 185 fatalities. [1] They don't publish a passenger-miles number, but there were about 5M passengers before they opened the Orlando section and then 1.6M long-distance and 1.1M short-distance in 2024. If we guess that the first 9.5 months of 2025 looked like 2024, that's an additional 1.3M long-distance and 0.9M short distance. In total that's 2.9M long-distance trips and 7M short-distance. Based on the distances involved, I'm going to guess 200mi for long distance and 50mi. This gives us a total of 930M passenger-miles, and 20 deaths per 100M passenger miles.
For cars, Florida seems to have 1.42 deaths per 100M vehicle miles. If we guess that there's an average of 1.4 people per car, this is ~1 death per 100M passenger miles.
So Brightline is about 20x more deadly per passenger-mile (counting people inside and outside the vehicle) than driving, and the article isn't fearmongering. The Department of Transportation uses $13.7M for the statistical value of a human life, and 185 fatalities is $2.5B. And it's going up at about $0.5B/year. [2] Without safety improvements, in something like seven years the ongoing societal cost in deaths will have grown larger than it's initial $6B construction cost.
I do expect this to get better over time: some of these fatalities are people not being used to the trains, and as that changes I expect fewer people to do things like cross the tracks where they don't have good visibility or under an assumption that the only trains that might come by are slow freight trains. The government has also been making improvements like adding fencing, and you could probably fence the whole thing for under $100M [3]. Getting Brightline to be less deadly than cars will be a lot of work (a 20x reduction is hard) but since trains elsewhere manage to be much safer this seems plausible.
The key takeaway for me, however, is that people who advocated for Brightline on the idea that it would reduce deaths made a pretty serious mistake. That Brightline would get cars off the road was a standard talking point, and people seemed to assume that this would be be positive from a traffic fatality perspective. Here's the Rail Passengers Association saying this explicitly:
Regular train service along the corridor would remove as many as three million cars from regional highways each year, reducing both commuter stress and road fatalities. With 300 drivers killed in road accidents between 2004 and 2008, Interstate 95 has been ranked as the deadliest highway in the United States. A passenger rail alternative will thus save lives.
Advocates weren't wrong in the general case, since trains are normally much safer than cars even counting non-occupants. The problem was Brightline's specific route, with hundreds of grade crossings in densely populated areas and unfenced tracks that divide many places people want to move between. This is something people who know trains well should have been able to anticipate.
Since Brightline is following the laws, and there are strong legal protections for railroads, even if we decided Florida would be better off with Brightline shut down, it would be very difficult and would likely require federal legislation or a massively expensive buyout. So the best we can realistically do is safety infrastructure improvements, and there's already a lot of political motivation here. A 20x decrease in fatalities sounds very difficult, but combination of additional fencing, improved crossings, and increasing public familiarity with the trains may be able to bring fatalities down to where the train is at least competitive with driving.
[1] Arguably you should not count some fraction of the 37 suicides, as
some of the people may have otherwise have chosen other ways to kill
themselves. But even if we don't count all of them, dropping
fatalities from 185 to 148, the bottom line doesn't change very much:
16x more deadly instead of 20x.
[2] The Atlantic says 42 deaths in 2024. At $13.7M/death this is $575M.
[3] The corridor is 235mi, which is 2.5M ft when you count both sides. Installing fencing might be $25/ft, so $63M.
Comment via: facebook, lesswrong, mastodon, bluesky, substack
2025-10-25 21:00:00
I help organize a contra dance in a crowded dance hall, and we've been considering using far UVC to clean the air, reducing infection risk from COVID, flu, and other airborne pathogens. We recently polled the group, and far UVC was very popular, so I think it's likely we'll roll it out. But how should we position the lights?
When I first looked into this, with help from UV researcher Vivian Belenky at the Columbia Center for Radiological Research, they used the OSLUV modeling tool to estimate the efficacy of four lamps on portable 10ft stands, one in each corner. As I started looking into the logistics of setting this up, however, having tall stands on the dance floor seemed difficult to do without some combination of taking up a bunch of floor space and providing a tripping hazard.
Instead of putting them in the corners, a single tall stand in the middle of the stage would be a lot more practical logistically. But would having four lamps so close together be an exposure risk? And how much air cleaning efficacy would we lose?
I prepared two scenarios in the modeling tool, each with four Aerolamps in a 66ft x 40ft x 23ft room. The first case is the one Vivian and I had worked in, with a lamp 10ft up in each corner (config):
The second is what I'd prefer to do, four lamps at the front of the stage, 13ft up (10ft stand + stage height) in the center (config):
On safety, the modeling software evaluates against ANSI/IES RP-27.1-22 using ACGIH (2022) TLVs for 222 nm, and both scenarios are well below limits, even standing in the part of the floor with the highest exposure. [1]
On efficacy, average fluence was 0.289 uW/cm2 (stage) vs 0.306 uW/cm2 (corners), a 5.6% decrease. [2] This is small enough that I think we should go with the logistically easier one, and put them on a single stand on stage.
[1] Specifically, measured over an 8hr period, it estimates maximum
skin and eye doses as:
| Corners | Stage | |
|---|---|---|
| Skin | 16.68 mJ/cm2 | 26.08 mJ/cm2 |
| Eye | 30.41 mJ/cm2 | 39.45 mJ/cm2 |
These are low enough that they'd be safe even for full days: the place where any of these scenarios gets closest to the limit is eye exposure in the stage scenario, and that would require ~30hr of continuous exposure to reach the 8-hour TLV.
Of course if you are moving around the room, as dancers do, your dose is far lower, because you won't be in the single worst place the whole time. The weighted skin and eye doses, again for an 8hr period, are:
| Corners | Stage | |
|---|---|---|
| Skin | 0.12 mJ/cm2 | 0.18 mJ/cm2 |
| Eye | 0.62 mJ/cm2 | 0.81 mJ/cm2 |
[2] The actual effects on pathogens are not linear in average fluence, however, because there are two effects working in opposite directions:
Some pathogens are inactivated with very low levels of UV, and the coverage pattern in the stage case has more areas with no coverage than in the corners case.
Other pathogens are only affected at higher levels, and the maximum fluence in the stage case is higher.
The OSLUV tool gives estimates that translate the full fluence distribution into inactivation to account for these effects. The overall impact, however, was very small (sheet). I saw decreases of the UV equivalent CADR of 5.7% for bacteria, 5.7% for coronaviruses, 5.1% for influenza, and 6.9% for phages.
2025-10-23 21:00:00
I've had a lot of people reach out to me who are interested in working on biosecurity, but have a background in software engineering / computer science. A lot of these conversations have looked something like:
A: I'd be really excited to work on biosecurity, it seems really important and relatively neglected. Are you hiring for software engineers at SecureBio?Me: I wish we were, you seem really great! But I don't know when we will be, depends on funding and some strategy questions.
This has now changed, and SecureBio is now hiring for two different software engineering roles that don't require a biology background:
NAO: Bioinformatics Engineer. An in-person role on the project I lead, developing a metagenomic biosurveillance system to detect stealth pathogens.
AI: Software Engineer, AI Safety and Biosecurity. A remote role on the project Seth leads, evaluating frontier AI systems, with a focus on biosecurity and misuse risk.
Consider applying?
Happy to answer questions!
Comment via: facebook, lesswrong, the EA Forum, mastodon, bluesky
2025-10-20 21:00:00
An honest attempt to describe what you're technically supposed to do if you follow the posted policies. I don't think anyone actually expects you to do this!
Great to hear that you've decided to attend your first contra dance! It's really easy to get started, they're a lot of fun, and it's a friendly and welcoming community. You just show up, the caller tells you what to do, and in a few minutes you're dancing. It's got the best learning curve out there!
There's one minor exception, however, which is that some dances are "fragrance free". For these you'll need a little prep: plan to start getting ready about three weeks before your first fragrance free event. I know this can be a bit more time than you were expecting to invest before learning whether this is an activity you'd enjoy, but trust me: it's worth it!
It can be a little hard to figure out whether a dance you're considering attending is fragrance free. While some dances list it on the homepage, you can't count on that. For example, it could be at the bottom of the code of conduct or listed on a dance etiquette page. The safest thing to do is to read the whole website, but of course that's a ton of work so you might want to write to the organizers.
Once you find the policy, it probably looks something like:
These Dances are Fragrance Free - please do not wear perfume, cologne, or other scented products, as some of our dancers are chemically sensitive, and experience discomfort when exposed to these materials.
Read it carefully! While many people initially interpret these policies to prohibit perfume, "scented products" includes soap, shampoo, conditioner, deodorant, laundry detergent, etc. I recommend you start three weeks before the event, and spend a week noting the ingredients on each product you use. Read them over, looking for the words "fragrance" or "parfum". If you don't see those, there's still some chance that it's a scented product, unfortunately: sometimes individual fragrance ingredients are mentioned by name instead. I recommend taking a picture of the ingredients and uploading it to an LLM with a prompt like "are any of these ingredients fragrances"?
Note that some products will say "unscented", but still have fragrances. This is very confusing, but the basic idea is that an "unscented" product is intended not to smell like anything, and might include "masking fragrances" to cover the scents of the ingredients. Products that say "fragrance free" are a better bet, but the term is not heavily regulated and there are products out there like this eucalyptus lavender soap bar that say "free from any fragrances" but also have strongly scented essential oils:
Two weeks week before the event you should have your list of the products you need to find substitutes for. It's the same deal as before: analyze ingredient lists on potential replacements, and again LLMs may be useful. Here are some product lists that might be helpful in getting started: EastBayMeditation, FGC. If the cost is a burden, and a full set of personal care products can be a substantial investment, consider writing to the organizers to ask if they have a fragrance-free fund.
With medical products, like a medicated shampoo that happens to be scented, sometimes a fragrance free replacement is not an option. I'd recommend talking to the organizers: they may be willing to consider an exception. This is another reason to start early, since most of these events are organized by committees and can take a while to come to a decision.
About a week before the event you should have acquired all your replacement products: now it's time to start using them! The goal is that by the time you attend the event you no longer have any lingering fragrances on yourself or your clothes. For clothes in particular scents can last a long time, so the safest thing to do is clean your washing machine (wash the machine with baking soda, then again with vinegar) and then wash your clothes twice. If you use a laundromat there aren't any good options, since fragrance free laundromats are essentially not a thing, but if you ask around you may be able to find a friend who has their own machine and either already takes a fragrance free approach or is willing to help you out.
At this point, you're ready to attend the dance! Make sure you're wearing clothes that have been washed since you transitioned away from scented products. It's also a good idea to bring your own hand soap: it's sadly common for fragrance free dances to have scented products in their bathrooms. I hope you have a great time!
While this post is using satire to make a point, my core view is that it's fine for dances to have whatever approach to fragrances they choose as long as they're thoughtful about what they actually expect attendees to do and communicate it clearly. When I've written about this before I've read a lot of comments from people who don't see a problem with the status quo. My target with the satire here is dances that put a few words about a policy on their page that they don't actually expect people to follow, don't put effort into ensuring potential attendees see, and sometimes even blatantly subvert by having scented products available at their dances.
Comment via: facebook, lesswrong, mastodon, bluesky, substack