Whose breath are you breathing?

https://www.rnz.co.nz/news/in-depth/470690/whose-breath-are-you-breathing

by tigerlily • 4 years ago

110 76 4 years ago

rnz.co.nz

ClosedPistachio• 4 years ago

Any recommendations for a good portable CO2 monitor?

greyface-• 4 years ago

https://aranet.com/products/aranet4/

Aardwolf2• 4 years ago

"Connect your device to the app to view, track and analyze your data from the last 7 days"

In a time where gigabytes are trivial (megabytes is enough for hundred thousands of measurements anyway here), why do such limitations like "7 days" still exist?

If there's a way to get a CSV or similar file you can analyze on any device you want, then we're talking

ahaucnx• 4 years ago

Shameless plug.

We are maintaining an open source / open hardware indoor air quality project that measures CO2, PM2.5, temperature and humidity [1].

We use the same CO2 Sensor (Senseair S8) as the device in the article and I can confirm that it's very accurate.

[1] https://www.airgradient.com/diy/

cfcf142• 4 years ago

I hadn't considered how bad public transport might be in terms of ventilation, but it makes sense. I wonder how bad the London tube might be on a busy day?

It's unfortunate that research on the impact of Co2 concentration on cognitive function and general wellness is so inconclusive (ie: effect size of high concentration on most tasks seems small), when subjectively it feels really high.

Some years ago I did some datascience work with a housing association wherein they installed high-frequency sensors in various rooms of housing units across the country (with the explicit consent of the inhabitants, data anonymized) with the intent on understanding how building properties and use correlated with the sensor data. In general there was (and still is) a lack of understanding how to model the relationship between things like building material, climate, occupancy, tenant behaviour and negative outcomes like mold growth, fuel poverty/health outcomes, and so on. I mean - I'm not saying there's no understanding, but it's definitely a field where more work is needed.

Anyways, one of the things I found most shocking is that in many of these flats, Co2 concentrations would get mind-bogglingly high in bedrooms during the months where tenants would likely have the windows closed (this is something you can infer by temperature gradients and heating usage). By mid-way through the night, some individuals were in rooms with 4k+ co2 ppm. A common side effect of breathing air with such a high concentration is waking up feeling groggy, disoriented, or with a headache. But what are these people supposed to do - many of these flats were low-income housing, so they're badly insulated to begin with, and they probably can't afford the heating bills of keeping windows open for ventilation.

Sorry for the long story - but the point is that there are many negative health externalities associated with poor ventilation in buildings and interior spaces, and at least we're starting to get attention on the problem now with covid. Hopefully this leads to improvements across the board.

moneywoes2• 4 years ago

Does the AV help?

jwilk• 4 years ago

What's AV?

cfcf142• 4 years ago

(Assuming you mean AC) - HVAC systems are generally designed to keep air flowing through the building optimally, which may include control systems for attenuating fans, exterior building air intake, and whatnot as a function of sensor measurements. I'm not sure how often CO2 is taken into account during building design or operation to be honest, aside from rough targets on designed occupancy rates and volumetric estimates of airflow.

In the UK, most buildings are naturally ventilated. There's no mechanical ventilation moving air around automatically, you gotta open your window if you want airflow. In the winter this generally puts people between a rock and a hard place: either you are slightly cold and sitting in a stuffy roof, or you open a window and are REALLY cold and also go broke from the energy bills :P

bobthepanda4• 4 years ago

London’s tube is particularly bad because of its history running steam trains, of which the residue is still present on walls and ceilings. The Tube is also poorly ventilated due to its age (when this was less considered) and the fact that vent shafts open into places that also have bad air quality.

NYC performs relatively better, it sits close to the surface with frequent vents. There have been simulated bioterror attacks that show the threat in the subway would dissipate quickly due to the ventilation.

The article mentions a bus. I would expect the bus to ventilate more poorly; trains have many doors per car and they simultaneously open for the entire stop in the station, but a double decker only has two doors, the back open to let people off and closed shortly after that’s done, and the top deck has no doors at all.

TylerE• 4 years ago

I am extremely skeptical of your claims re: London.

Steam hasn't operated on the Underground in 115 years, and only ever on a small minority of lines.

dredmorbius2• 4 years ago

I'm not sure there's a significant difference between depths of most of the London and New York subway systems.

Most of the London Underground is cut-and-cover tunnels sitting just below ground level (2-6m). The Thames Tunnel is 24m below ground level. The deepest station is Bull & Bush, Hampstead, at 57m (180ft) underground:

https://londonist.com/2015/10/how-deep-does-london-go

https://londonist.com/london/transport/how-deep-is-your-comm...

The NYC subway also uses extensive cut-and-cover routes, though deeper bores exist. The deepest station, at 191st St. (LRI) is 180 ft. (54m) below ground. About the same as the London Underground.

https://untappedcities.com/2013/06/26/deepest-highest-subway...

https://www.nycsubway.org/wiki/Chapter_14:_Engineering_Featu...

blintz• 4 years ago

On the public transit point: fun fact, BART (a large SF/Bay Area transit system) trains replace all of the air in each train car every 70 seconds, which is a much higher rate of airflow than most other public spaces. Since they also use MERV 14 filters, there may be a disconnect between CO2 readings on BART (or other transit systems with aggressive filtration) and the true risk of catching a respiratory virus.

rossdavidh2• 4 years ago

Interesting, but I see two big issues that render the data nearly meaningless:

1) does CO2 correlate well to spit droplets? they mention this (alleging that places with more talking have more spit droplets than ones without) but present no data. Also, does CO2 on public transport involve any exhaust from the vehicle? Are people in gyms breathing a lot with their mouth closed, producing more CO2 but not talking (or otherwise producing spit droplets) nearly as much. Lots of ways this could be not very correlated.

2) does quantity of spit droplets really correlate to likelihood of getting infected? Viruses are replicators. It is not at all obvious to me that 1/2 the number of viruses means 1/2 the risk of getting infected. It might not even result in a significant drop at all. Theoretically one droplet containing the virus is enough to infect you, and if infected it replicates. The operative factor is how well your immune system recognizes the threat and produces antibodies, not how many virus copies were there originally. One drop was enough to infect just over half of a young, healthy experimental subject group: https://www.science.org/content/article/scientists-deliberat...

pessimizer• 4 years ago

The operative factor is how well your immune system recognizes the threat and produces antibodies, not how many virus copies were there originally.

These probably aren't independent, and are occurring at the same time. So while a very small amount of virus is replicating, the immune system is mounting a defense, slowing down that replication. The virus may never get to a significant amount (although the immune response might knock you on your ass.)

On the other hand, if you start with a ton of virus already, you'll be dealing with the immune response and the direct effects of the virus at the same time, and the virus may overwhelm or even limit the immune response.

rossdavidh2• 4 years ago

True, but even a large number of droplets will not result in "a ton" of virus, if by "a ton" we mean "similar to what will result if you get sick". A sick person breathes out a lungful with every breath, so obviously a sick person contains far, far more copies of the virus than that.

Put it another way. If your immune system recognizes the virus already, it matters little whether you get one droplet or a thousand, it will beat it because it has a several-day head start in doing so.

If, on the other hand, your immune system does not already recognize it, then it will not begin to see the problem, and thus will not begin to react, until it has replicated up to a large amount, where "large" is some amount greater than either one droplet or one thousand will give you. So, the consequences of getting exposed to 1/2 or 1/10 of the number of copies of the virus, is basically nil, because an exponential rise will be needed in either case to get up to the level where your immune system notices a problem.

Either your immune system already recognizes the virus as a problem, or it doesn't. I neither case does the dose matter, so long as the dose is big enough to start the process. And that probably doesn't take much.

dentemple• 4 years ago

The article is focusing on ventilation and air circulation. Poor ventilation results in increased CO2 levels, and it does so in a predicatable, measurable amount.

We also know that poor ventilation increases the likelihood of catching covid from an infected individual. So measuring the level of a space's ventilation is not meaningless data, even if it doesn't translate 1-to-1 with transmission rates.

mannykannot• 4 years ago

There are two scenarios in which halving the number of droplets inhaled has little effect on the risk of being infected, and two where it is moot.

The ones where it is moot is those where either you you are already infected or no-one is.

Halving the number of droplets will have no effect if droplet inhalation is not causal in transmission. In this case, there is plenty of evidence that it is, in fact, the primary mode of transmission.

It would also be the case when, even at the lower droplet count, one is likely to become infected. This is essentially the scenario in your second point.

None of the above are the case in a typical bus ride today, and for such, it is reasonable to suppose, as a first approximation absent further evidence, that risk is correlated with the degree to which one is rebreathing other people's exhalations, even though one can postulate that it is also correlated with other factors.

One can question the source of the CO2 on a bus, but the measured values reported here are significantly above those measured by busy urban roads, where 1000ppm is considered vary high. If the bus is leaking CO2 into the cabin to any significant degree, there are more immediate health concerns.

Demanding near-perfect data before considering its implications can be a way to avoid issues.

groby_b3• 4 years ago

1) Spit droplets is much less of a problem than aerosols. You can solve that problem well with keeping distance. Aerosols are a bigger problem - they travel further and linger.

All the studies I've seen so far correlate CO2 with aerosol levels. If spit droplets are a concern, I have no idea.

2) Covid studies so far have shown that there's a minimum level of viral load required for an initial infection, and they have also shown that there's a correlation between initial dose and severity of infection. So, yes, how many virus copies were there originally matters very much.

In general, this has been explored in a large number of studies. I'd suggest at least a cursory research before claiming issues that "render the data near meaningless".

whoomp123422• 4 years ago

it would be implied. in an indoor setting most of CO2 comes from human exhaust

noja• 4 years ago

It sounds gross. But:

i) if we all drove cars, the result would also be bad

ii) I wonder if there are benefits from this (stronger herd immunity)

starkd• 4 years ago

You might also wonder how this applies to supposed good bacteria, and the transfer if bacteria across people. Much like the gut microbiome, social situations might be essential. After all, people have been gathering in close quarters for a variety of reasons for millenia.

thinkingemote3• 4 years ago

Whilst in wondering mood, think about behaviour modifying organisms who want and alter host social behaviour so that they spread more.

E.g. toxoplasmosis

There's been some research done on whether the flu is an STD making people more...sociable. Perhaps asymptomatic COVID infections encourage people to mingle more? Or maybe other actual STDs do? The existing science is weak, troublesome (it's very hard to research ethically) and few but I love the idea of it.

graeme2• 4 years ago

Herd immunity through infection has never worked. It's incoherent even as a concept: to prevent infections, get infected?

There are a few diseases better to get as a kid than as an adult, but we mostly have vaccines for those now. And respiratory viruses aren't included in the category of those we need exposure to for immune system development.

In 2003 Graham Rook proposed the "old friends hypothesis" which has been described as a more rational explanation for the link between microbial exposure and inflammatory disorders.[20] The hypothesis states that the vital microbial exposures are not colds, influenza, measles and other common childhood infections which have evolved relatively recently over the last 10,000 years, but rather the microbes already present during mammalian and human evolution, that could persist in small hunter-gatherer groups as microbiota, tolerated latent infections, or carrier states. He proposed that coevolution with these species has resulted in their gaining a role in immune system development.

https://en.wikipedia.org/wiki/Hygiene_hypothesis

ars2• 4 years ago

It's incoherent even as a concept: to prevent infections, get infected?

What's confusing? Get infected once, avoid tens of infections. If your immune system "forgets" the immunity after 6 months (which is the case for COVID), then every 4 months get exposed, you won't get actively sick since you still have some immunity, and you'll keep your immunity high.

ekianjo2• 4 years ago

if high CO2 equals more risk of contamination then Japan should be getting large transmissions of COVID in over-saturated trains on a daily basis, but it does not. So this data seems more junk than anything else.

SapporoChris• 4 years ago

I think you are being hasty. Japan has amazing mask discipline which could account for the differences. Also, like many countries train travel was reduced during the pandemic as more companies began allowing telecommuting and flexible hours.

Second, I found a wealth of articles just by searching: japan train ventilation

Train operators already have good methods in place: https://www.jreast.co.jp/e/customer_support/corona-info/inde...

It looks like the frequent stops are very good at ventilating the trains: https://www.nippon.com/en/news/yjj2020112601115/

But they recognize the the problem: https://eandt.theiet.org/content/articles/2020/07/trains-and...

dzhiurgis• 4 years ago

So I assume you at least have some data on japan trains co2?

graeme2• 4 years ago

What's the CO2 in those trains? Japan tends to have great ventilation and has CO2 meters around the place.

It isn't impossible to ventilate a train well. I've been on a train with CO2 around 600 and another around 3,000. Air system design matters

However, one train in Japan did have very high levels based on a transport ministry study: https://www.asahi.com/ajw/articles/14515055

ekianjo2• 4 years ago

It isn't impossible to ventilate a train well.

Not for the trains at rush hour in Tokyo.

amelius• 4 years ago

Lately I hear about more COVID cases that presumably started on an airplane. Therefore I am now wondering how great these ventilation systems on airplanes really are, compared to, say, those in restaurants and theaters.

hugs2• 4 years ago

We don't hear how great the ventilation is in all the lines one has to wait in to get on the plane. If someone got COVID after a flight, it's hard to tell if they got it while the plane was in the air, or while waiting to board in or near the jetway.

unsupp0rted• 4 years ago

The counterintuitive thing is people stand in lineups or sit shoulder-to-shoulder in airport seating with their masks off sipping coffee or eating chips, then get on the plane and put masks on.

It's possible (but not proven) that inverting this would be much safer, since on the airplane the air gets exchanged a lot.

technothrasher• 4 years ago

I'm currently dealing with a Covid infection that, given the timing involved, I'm pretty sure I got on an airplane. It could have been at the airport, I suppose, but the guy sitting in the seat next to me sniffling and coughing, and with no mask on gives me a pretty good idea where I got it.

latchkey• 4 years ago

"CO2 level on this @VirginAtlantic A330 indicates that it isn’t really safe to remove your mask shortly after the doors have closed. Hopefully this number will drop soon."

https://twitter.com/alexr/status/1523125114371719168

"Hey @united, it'd be great to see better fresh air circulation in your Austin airport Club. The box in the photo is a CO2 sensor measuring parts per million, and 1117 was pretty high for just a few people in the bar area at the time. Above 1000 cognitive function can be impaired."

https://twitter.com/brianbehlendorf/status/15407875450338181...

shiftpgdn• 4 years ago

Once the plane is in the air? Fantastic! It’s when the plane is on the ground and the main power and filtration is off is where the danger is. On my last few flights I’ve brought a high quality co2 meter and it consistently hit 3000-5000PPM in the time between boarding and when the plane was moving.

dQw4w9WgXcQ• 4 years ago

What is the best response here, carry an emotional support plant / tree?

fortran77• 4 years ago

Airlines never stopped allowing CPAP in flight even though the US Government warned it is extremely dangerous to be around because it aerosolizes and projects virus particles.

Even NPR summarized the risks. https://www.npr.org/sections/health-shots/2020/03/27/8222116...

Airlines, and the regulators, are only worried about optics, not our health.

thamer• 4 years ago

Covid aside, a reading of almost 6000 ppm in the bus is extremely high, at this level there is a clear impact on cognitive function.

See this study[1] in Nature that measured the effects of CO2 at 1000, 3000, and 5000 PPM. Quote: "For the Psychomotor Vigilance Test, the probability of achieving an accuracy score of >90% decreased in a dose–response like fashion from 79.5%, 74.7%, 73.4%, to 64.0% for 600, 1200, 2400, and 5000 ppm, respectively".

Another study[2] tried to establish the effect on response time, finding that "For every 500ppm increase, we saw response times 1.4-1.8% slower, and 2.1-2.4% lower throughput."

For a more pop-sci take on this, see this Tom Scott video where a subject is placed inside of an airtight chamber where the CO2 gradually increases, with a major impact on their brain function: https://www.youtube.com/watch?v=1Nh_vxpycEA

[1] https://www.nature.com/articles/s41526-019-0071-6

[2] https://iopscience.iop.org/article/10.1088/1748-9326/ac1bd8

BruiseLee• 4 years ago

6000 ppm is a normal level after 1 hour meeting in a closed conference room. Assuming non-openable windows (which is normal in modern offices).

groby_b3• 4 years ago

It decidedly isn't normal unless your HVAC is supremely bad and the room's way too small for the group.

I have so far not been in a conference room even scratching the 2000 ppm level after an hour. (Well, OK, I only leave my meter behind. At 1200ppm, I consider the level excessive and leave. But I've kept measuring to see how willing people are to burn their health to be in the office with others)

bsedlm• 4 years ago

all of it, I hope...

preferably mostly plants

a3w• 4 years ago

Scientists estimate that 50-80% of the oxygen production on Earth comes from the ocean. So yes, phytoplancton is an MVP. Good thing we won't kill life in the ocean any time soon due to climate change, rather only some of it.

7373737373• 4 years ago

Title reminds me of this:

Nowadays, at least in the population of the industrialized nations, about 40 percent of the nitrogen contained in the human body has already taken part in the Haber-Bosch synthesis.

(from the German https://en.wikipedia.org/wiki/Haber_process article)

flobosg• 4 years ago

This reminded me of an undergraduate Physics professor who made us estimate the fraction of molecules in one breath that had been exhaled by Jesus. Fun times.

Thiez• 4 years ago

I remember a question that was similar in nature; suppose you (accidentally of course!) drop a full but opened bottle of vodka in the sea. That night there is a huge storm that mixes all the water in the oceans so that the vodka is distributed perfectly. How many alcohol molecules (from that original bottle, ignoring any existing alcohol, evaporation, and other chemical or biological processes that would interfere with the answer) are in a liter of seawater?

Sadly I do not recall the answer but it was way more than I expected. The Avogadro constant is a lot.

whoomp123422• 4 years ago

huh, all the places I would never go have terrible air.

worik2• 4 years ago

Lucky you.

Some of us want to catch the bus. Some of us have to

webnrrd2k• 4 years ago

In a related, but much more personal note: it turns out that we are breathing, on average, one molecule of Ceasar's last breath [1]. And Jesus, Buddah, and a lot of other people.

[1] https://www.irishtimes.com/news/science-asserts-we-are-all-p...

(I know, it's probably mostly BS -- I'd bet most of the last breath has been absorbed into the ocean, or plants, or whatever. But, over my lifespan, I've probably sucked down atoms of Jesuse's breath during his lifespan. With that, who needs holy relics.)

Whose breath are you breathing?

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