2025-11-23 21:00:00
It can be hard to get the kids to practice their instruments. Sometimes they're having trouble focusing, don't like their assigned piece, or are just grumpy. One thing I'll offer them in these cases is "busking practice".
The idea is, we'll pretend we're busking together. I'll start playing a tune they know, and they should do something that sounds good. That could be playing the tune with me, making up a harmony, or just figuring out a single note that sounds ok and playing patterns on it. If they make a mistake, we keep going. If they can't figure out what to play, we keep going. We're practicing performing. It helps that they're pretty motivated to get good at busking, because they know they can earn money that way.
Working on the pieces the teacher assigns (if you have a good teacher!) is very efficient a turning time on an instrument into becoming a better musician. But if willpower is the limiting factor and not time, and especially if the alternative is a super short practice or no playing at all, the important thing is just picking up the instrument and playing something. I like that busking practice give us some structure for this, and lets the kids build up their performance skills.
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 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.
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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.
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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!
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