9 ms·

Analyzing Carbon Dioxide levels while attending IETF-115 in London, UK

183 points by zdw 4y ago

nicoburns 4y ago
This seems to pretty well justify my recent approach to covid precautions which is to wear an N95 mask on public transport (and nowhere else), and to try and avoid social situations in densely packed rooms where practical.
- MuffinFlavored 4y ago
  does wearing a mask stop from spreading if you have it or stop you from getting it from others or both?
  - Baeocystin 4y ago
    An N95 does both, to a highly effective degree.
    - deleted 4y ago
      [deleted]
    - timr 4y ago
      We have no good evidence for this claim. The only studies involving n95 masks and respiratory illness were conducted in hospital settings (i.e. don't reflect "normal" life), have high risk of bias (i.e. were small and were not randomized, controlled trials), and have shown mixed results. This is the WHO review that summarized the existing evidence for masks at the start of the pandemic. There were 4 studies on n95 masks in hospitals: https://www.thelancet.com/journals/lancet/article/PIIS0140-6 https://www.thelancet.com/journals/lancet/article/PIIS0140-6... Additionally, this is the most comprehensive review of mask literature I am aware of. It explicitly states that: > At least ten studies evaluate the clinical efficacy of different types of masks compared to one another, but without a no-mask control group most provide little insight into mask efficacy. > Four RCTs, four meta-analyses, and one prospective cohort study found surgical masks were non-inferior to N95s for protection against respiratory infections, and one found evidence that N95s provide greater protection than medical masks against self-reported clinical respiratory illness but not ILI. However, a recent review found that evidence that N95s protect healthcare workers from clinical respiratory infections at all is “low quality". One meta-analysis of particular note, an April 2020 preprint of a Cochrane review of clinical evidence for both surgical and N95 masks, “did not find any differences in the clinical effectiveness of either type of mask in the setting of respiratory viral infection transmission to healthcare workers,” although the review’s final November version omitted this language. https://www.cato.org/sites/cato.org/files/2021-11/working-paper-64.pdf https://www.cato.org/sites/cato.org/files/2021-11/working-pa... We simply don't know if n95 masks provide any protection -- personal or otherwise -- in the real world. That is the only honest answer to the parent's question. Everyone who claims otherwise is extrapolating from laboratory experiments, low-quality observational data, or (this is probably the most common) hearsay.
      - HyperSane 4y ago
        Why do surgeons wear masks?
        MobiusHorizons 4y ago
        Not an expert, but as I understand it, surgeons could be exposed to much more than airborne viruses (bacteria, bodily fluids, etc). So masks would be worn for more possible reasons. It’s a good question though, I hope someone knowledgeable answers it.
        azakai 4y ago
        Surgical masks and face shields are indeed designed specifically to protect from fluids. That is very important too. Separately from that, when there is a risk of airborne transmission as there is with Covid, doctors and nurses will wear appropriate masks like N95s.
      - andbberger 4y ago
        nonsense, N95s are highly effective and if you want to make a good faith argument that they're not try citing the new england journal of medicine and not the fucking cato institute, good lord
        deleted 4y ago
        [deleted]
      - azakai 4y ago
        > We simply don't know if n95 masks provide any protection -- personal or otherwise -- in the real world. That is simply not true. First, doctors and researchers consistently say that N95s are known to provide protection against Covid. Second, this is the first google result on that topic: https://www.cdc.gov/mmwr/volumes/71/wr/mm7106e1.htm https://www.cdc.gov/mmwr/volumes/71/wr/mm7106e1.htm Quoting from that CDC page: > What is already known about this topic? > Face masks or respirators (N95/KN95s) effectively filter virus-sized particles in laboratory settings. The real-world effectiveness of face coverings to prevent acquisition of SARS-CoV-2 infection has not been widely studied. > What is added by this report? > Consistent use of a face mask or respirator in indoor public settings was associated with lower odds of a positive SARS-CoV-2 test result (adjusted odds ratio = 0.44). Use of respirators with higher filtration capacity was associated with the most protection, compared with no mask use. > What are the implications for public health practice? > In addition to being up to date with recommended COVID-19 vaccinations, consistently wearing a comfortable, well-fitting face mask or respirator in indoor public settings protects against acquisition of SARS-CoV-2 infection; a respirator offers the best protection. You can say that that might be just correlation, but as those quotes mention, we do know how N95s work: they filter viral particles. That is easy to prove in lab settings. Real-world settings involve more factors, like how well-fitting the mask is, but it would be very surprising if a good N95 properly used did not offer any protection! N95 masks work. It's a good idea to wear one when relevant.
  - VancouverMan 4y ago
    Some long-term, large-scale studies of the effects of widespread public masking have been performed recently. For example, one lasting over 1.5 years was done in the province of Ontario, Canada, involving approximately 15,000,000 participants, in environments ranging from dense urban settings to sparse rural ones. In Ontario's largest and densest population center, Toronto, the duration this study was about 2 years in length. It was conclusively demonstrated that widespread public masking does not prevent infection, and it does not prevent transmission, of airborne viruses. It was conclusively proven that such masking did cause accessibility problems, it did cause significant social disruption, and it did cause environmental damage, among numerous other harmful effects.
    - HyperSane 4y ago
      Can you provide a link to this study? If masks don't work then why do surgeons wear them?
      - samatman 4y ago
        To the latter question, it's to prevent droplets of spittle from landing on exposed tissue. There are pathogens which spread by droplets, rather than aerosols, the Sars2 virus doesn't happen to be one of them. Yes, if you spit directly onto an open wound or mucous tissue, but it doesn't live long on surfaces, and the droplet-fomite route is how that vector of infection works.
        HyperSane 4y ago
        "prevent droplets of spittle from landing on exposed tissue" Isn't tiny droplets of saliva how most respiratory viruses spread?
      - lucb1e 4y ago
        They're joking that there were infections in the city despite mask requirements (surprise) and that mask requirements caused "significant social disruption".... At least I hope it's supposed to be a joke.
nicoburns 4y ago
Does anyone have any idea why CO2 levels would spike so high when a plane takes off?
- pstrateman 4y ago
  When planes take off there's often a strong smell of exhaust. Presumably the external air mix is just full of exhaust before they're at speed.
  - pornel 4y ago
    Or perhaps external air intake is closed/limited because of the smell.
- akira2501 4y ago
  I'm not exactly sure, but during take off the "packs" are typically disabled. This removes air conditioning and probably lowers the amount of air that would be circulating when they are enabled.
  - sokoloff 4y ago
    The air cycle machine (“packs”) are turned off if maximum power is needed (as their use requires bleed air, which takes power from the engine).
    - mleonhard 4y ago
      The author's DEN-LHR flight was on a Boeing 787 aircraft, which use electrically-powered air compressors [0]. They do not draw air from the engine. 787 maintain internal air pressure equivalent to 6,000 feet of elevation. All other commercial aircraft maintain 8,000 feet air pressure. I think most of my discomfort from long flights is due to altitude sickness. The only time I have slept on a long flight and awakened refreshed was on a 787. Jet engines use a neuro-toxic lubricant. Occasionally, some of this enters the cabin through the compressed air feed and poisons the passengers [1]. 787 passengers don't have this risk because the planes don't draw air from engines. [0] https://en.wikipedia.org/wiki/Boeing_787_Dreamliner#Interior https://en.wikipedia.org/wiki/Boeing_787_Dreamliner#Interior [1] https://pubmed.ncbi.nlm.nih.gov/24713335/ https://pubmed.ncbi.nlm.nih.gov/24713335/
jeroenhd 4y ago
One thing I wonder about, especially seeing the numbers during take-off: how well can an Aranet 4 sensor deal with changes in pressure and temperature? As I understand it, these sensors require (sometimes lengthy) calibration to remain accurate. For automatic calibration, the device needs to be in fresh air for 30 minutes, no closer than 1 meter from the nearest person. There is also a manual calibration method. I don't know how often calibration is necessary, but I also think this use case may not be what the sensor was designed to do.
- phphphphp 4y ago
  I think you might have it the wrong way round, as the product information mentions fresh air as a requirement for manual calibration, not automatic. "If a drift of the CO2 measurements occurs, calibration feature of the device should be used. Auto calibration mode is utilizing ABC algorithm whereas Manual calibration mode demands sensor to be exposed to fresh air." "CO2 sensor of the device is calibrated at standard atmospheric pressure. CO2 readings are pressure compensated and comply with the specifications down to 750 hPa. If the device has to be used at high altitude for a prolonged period of time, manual calibration of the unit should be performed for optimal performance. It is not intended to use the device higher than 4000 m (13 000 ft) above the sea level." https://cdn.bfldr.com/FS48XT6B/at/k9b9wjnv8f455crkp7846j/Aranet4_datasheet_v25_WEB.pdf https://cdn.bfldr.com/FS48XT6B/at/k9b9wjnv8f455crkp7846j/Ara...
- mox1 4y ago
  yea I recently started monitoring my homes CO2 levels with some DIY sensors. You need to enter your elevation above sea level or have a pressure sensor hooked up. So if the op set a static pressure I assume that would affect the readings a lot. Calibration is also just the sensor looking for the co2 floor (ie the lowest level possible). You need to do this weekly or monthly maybe..? Auto calibration just sets the lowest level it has recently seen as the floor.
  - ahaucnx 4y ago
    What was your experience with the DIY monitor that you build? I am asking because we maintain an open source / open hardware indoor air quality project [1] that we continuously update and I am interested to learn about missing features we might have. Did your build have a dedicated pressure sensor? [1] https://www.airgradient.com/open-airgradient/kits/ https://www.airgradient.com/open-airgradient/kits/
djmips 4y ago
I have a few thoughts. One: that even if the C02 seems fine, if the din of the room means everyone is shouting then viral dispersal will be much higher. Two: it seems like having fresher air, will be more costly in the winter unless people can put up with lower temperature. I wonder how effective an airplane filter really is with regard to viruses. Should buildings and enclosed spaces be redesigned to include better filtering and at what running cost will that be?
- kortilla 4y ago
  > wonder how effective an airplane filter really is with regard to viruses. Airplanes are far better than any normal indoor building space. It’s a constant blend of outside air that means the entire cabin’s volume of air is gone within something like 5 mins.
  - sampo 4y ago
    > Airplanes are far better than any normal indoor building space. But only when they fly. When you are waiting that 30 minutes sitting in the plane after boarding, the fraction of re-breathed air can get high. People have measured 2000 and 4000 ppm CO2 readings.
    - MichaelZuo 4y ago
      Looking from the chart it seems like the CO2 levels were elevated for the entire flight? As in it never dips below 1200pm on either the short haul or long haul flight. Also with the caveat in the article: "Note that the graphs below aren't calculated for altitude adjustment. Since planes are generally pressurized to an equivalent of 8000 feet, and senor drift is typically 3 per 1000 feet of elevation, it means that while in the air the CO2 levels are likely $24% higher than shown on the graph." It seems the logged numbers are underestimating it.
- hedgehog 4y ago
  On the energy item modern HVAC systems use a device called an ERV to greatly reduce energy loss to ventilation. No need to turn down the heat to get fresh air. The thermal plume associated with each occupant makes the problem a bit easier too, in general stale air heads to the top of the room because it's warmer and more humid therefore less dense. Not a new idea and some good models to look at. https://en.wikipedia.org/wiki/Energy_recovery_ventilation https://en.wikipedia.org/wiki/Energy_recovery_ventilation https://techxplore.com/news/2020-12-ventilation-easy-highly-effective-low-cost.html https://techxplore.com/news/2020-12-ventilation-easy-highly-... https://hackaday.com/2022/07/07/the-benefits-of-displacement-ventilation/ https://hackaday.com/2022/07/07/the-benefits-of-displacement...
thadk 4y ago
Several of us have built visualization tools which produce output a bit similar to the one in this article for the aranet4 unit. These can be found linked from: https://observablehq.com/@thadk/aranet4-explorer https://observablehq.com/@thadk/aranet4-explorer. Works best with the iPad app on an M1/M2 macOS computer. There are also several other ways to get the output such as a bleak project on GitHub (https://github.com/Anrijs/Aranet4-Python https://github.com/Anrijs/Aranet4-Python).
stuaxo 4y ago
I need to start using my Aranet 4, which case did you buy, I already dropped mine on the floor once and it felt lucky it didn't break.
- MobiusHorizons 4y ago
  Not the op, but it looked like the case that comes with Chinese iems (fancy earbuds)
  - hardaker 4y ago
    I am the OP :-) It's actually a "CASEMATIX Portable Credit Card Reader Case Compatible with Square Contactless and Chip Reader, Case Only", which was the best possibility I could find. It would be nice if someone would make a dedicated case for the aranet4 as it is fairly sensitive. I'm fairly happy with this cheap case, but I'd like something that was better fit and designed for air intake, eg.
cobertos 4y ago
The anecdote about being sleepy on a plane makes me wonder if we couldn't just modulate our CO2 intake as a sleep aid. I find it _incredibly easy_ to sleep on a plane, and I generally have a very hard time with sleep due to brain not turning off. I think it would be interesting to see if there's any correlation between restful sleep and CO2 levels too. Maybe change the CO2 level to higher to induce sleep, and then fall asleep, and then bring it back down to have a nicer sleep.
- avian 4y ago
  I would hate to have a machine in my bedroom that is capable of raising the CO2 level. I don't think anyone could convince me that it would not decide to suffocate me at midnight next 29th February or something, regardless of its safety features.
  - MobiusHorizons 4y ago
    I think the general idea would be to have a device that typically reduces co2 level through ventilation, and just turn it off at night. That would let your normal breathing add the co2.
    - lucb1e 4y ago
      I wouldn't like to take hours for my sleep aid to kick in, if I would need such a thing. Instead of the room, maybe a little device called blanket could be used, but I don't know how reliably people get out from under that if they get in the habit of associating under blanket = sleep = good, because it certainly wouldn't be good to be under that all night.
      - cobertos 4y ago
        Might help to have it on a schedule, like a thermostat has, or maybe more advanced like Nest does. Then it kind of tapers you into a sleep schedule. Wouldn't work if coming back from a late night out though
  - 4y ago
dataflow 4y ago
I've heard some people can (train themselves to?) tell when the CO2 level rises in the room. Has anyone here managed to? If so, do you have any tips on how (or whether!) to do this, and/or what it feels like (if it's possible to give any vague explanation in text)?
- zahrc 4y ago
  It feels stuffy. I get headaches and get tired. When you open a window it’s almost like instant relief
  - JohnBooty 4y ago
    Yeah the thing we've casually called "stuffy air" forever is, essentially, 100% equivalent with high CO2 levels. There are some other situations where non-"stuffy" air might have too much CO2, I guess. I guess you could pump CO2 into a room with cool, dry air. But barring a contrived situation like that, stuffy=CO2.
- quakeguy 4y ago
  That’s called grandpa-tells-you-to-go-sleep Syndrom, it is harmless usually.
- afusalan 4y ago
  > I've heard some people can (train themselves to?) tell when the CO2 level rises in the room. Has anyone here managed to? If so, do you have any tips on how (or whether!) to do this, and/or what it feels like (if it's possible to give any vague explanation in text)? The best indication is feeling sleepy. Once you become sleepy go outside and take deep breaths, then you understand the sensation difference between O2 and CO2.
  - dataflow 4y ago
    Unfortunately that doesn't seem to work for me. Right now my room has > 1200ppm CO2 (due to closed doors/windows) but I don't feel sleepy at all, or any differently (that I can discern) from when it's < 600ppm. Do you know if it needs to be significantly higher for that feeling to kick in? If so, approximately how much?
ahaucnx 4y ago
We do indoor air quality monitoring and see very different results across buildings. The biggest differentiator is if the building has mechanical ventilation and to what extent this mechanical ventilation uses fresh air vs internal circulation. In unventilated crowded spaces like e.g. classrooms, we regularly see CO2 exceeding 3500 ppm. [1] However in classrooms with a well designed ventilation system you can keep the CO2 < 1000ppm during the whole school day. What the author did in his hotel room to turn on the fan or play around with the A/C settings is a good idea but many hotels Hvac systems do not draw in sufficient fresh air and you will see high CO2 developments. [1] https://www.airgradient.com/open-airgradient/blog/we-measured-the-co2-level-in-a-classrooms-this-is-what-we-found-out/ https://www.airgradient.com/open-airgradient/blog/we-measure...
- icelancer 4y ago
  3500ppm? That would imply an average CO2 level well above 1000ppm. No wonder why it's impossible to stay focused in lecture halls...
  - MichaelZuo 4y ago
    Yeah, that really makes me rethink my entire education experience...
    - JohnBooty 4y ago
      ...you could always distract yourself by thinking about all of the political and military decisions that have been made throughout history, affecting millions and billions of human lives, in stuffy cramped rooms with excessively high CO2 levels. ...wait, that's not helping?
      - MichaelZuo 4y ago
        The utopia of adequate ventilation.
      - p1esk 4y ago
rufus_foreman 4y ago
I guess when I was born, background CO2 was around 330 ppm. Is there anything I can do to breathe air like that again in my house?
- batch12 4y ago
  Open a window?
  - rufus_foreman 4y ago
    It's 420 ppm outside now.
  - ad404b8a372f2b9 4y ago
    Background ppm is no longer at 330, so opening a window would not get you there. You would need to keep the window closed and remove more CO2 than you produce.
    - batch12 4y ago
      Fair point. I wonder if there is a big difference depending on where one lives. For instance, if one were to live in the country, surrounded by trees...
    - rufus_foreman 4y ago
      Yeah that's my question. How would I remove more CO2 than I produce. I've got the window closed, I have a few houseplants, and I am already considering getting rid of Mr. Tiddlesworth, my cat. Is there some sort of machine I can buy? Like direct air capture? I only need this in like two rooms of the house.
      - ad404b8a372f2b9 4y ago
        I don't think so. I guess what you want is a CO2 scrubber like they had in Apollo 13, but I don't know of any consumer, room-scale, ones. Plants make basically no difference sadly, in my room it gets to 1600ppm in under an hour just from me and my cat Gazpacho, although I've admonished him for breathing so much.
pfdietz 4y ago
That would be a worrying level of CO2 for the cockpit. https://www.newsweek.com/carbon-dioxide-levels-flight-deck-affect-airline-pilot-performance-1061068 https://www.newsweek.com/carbon-dioxide-levels-flight-deck-a...
Havoc 4y ago
Anybody know what the actual sensor inside that device is? Spec sheet doesn't seem to say
- bloggie 4y ago
  According to some quick duckduckgoogling for “aranet4 tear down” it could be this: https://senseair.com/products/power-counts/sunrise-hvac/ https://senseair.com/products/power-counts/sunrise-hvac/
  - jobigoud 4y ago
    Yes, the Aranet 4 is even featured on the front page of SenseAir. "We're incredibly proud to have our CO2 sensor Senseair Sunrise inside this popular product." The sensor itself costs $229.00 at co2meter.com.
FollowingTheDao 4y ago
This is not going to change anytime soon. No one really cares about staying alive; climate change, diet, COVID. And COVID is now endemic and a pandemic. So either quit your job or learn about staying healthy when exposed to viruses that deplete zinc and other nutrients. Zinc deficiency lowers Tertrahydrobiopterin, which lowers coupled NOS, which lowers your immune system (NOS2) and gives you hypertension (NOS3) and makes you mental (NOS1). The Lower zinc also gives you diabetes. PubMed links for anyone who cares, but you probably don't.
- stuaxo 4y ago
  Please post the links, I feel like I live i a weird opposites world, where in the sane world we would have dealt with Covid by now, and have sorted out clean air in our public spaces (and to some extent homes too).
  - FollowingTheDao 4y ago
    EDITIED TO ADD: Before taking Zinc get your Serum Zinc and RBC Zinc levels tested. Easy to do in the US if you have some money. Also get your Serum Copper and Ceruloplasmin tested since taking zinc at high dose for a while will lower copper since zinc creates Metallothioneins that capture the copper in the intestine before it can be absorbed. -- Hey, thanks for being curious! Science! Zinc and Tetrahydrobipoterin: https://pubmed.ncbi.nlm.nih.gov/31732151/ https://pubmed.ncbi.nlm.nih.gov/31732151/ The Gene GCH1 is central to making Tetrahydrobiopterin and uses zinc as a cofactor. https://www.uniprot.org/uniprotkb/P30793/entry https://www.uniprot.org/uniprotkb/P30793/entry The zinc coupling of NOS via GCH1: https://www.ahajournals.org/cms/asset/2cc8b7a0-a31a-4759-bc8d-da0d1f512dcf/7ff2.jpg https://www.ahajournals.org/cms/asset/2cc8b7a0-a31a-4759-bc8... Uncoupled NOS makes a lot of superoxides, BAD!: https://www.liebertpub.com/cms/10.1089/ars.2013.5566/asset/images/medium/figure5.gif https://www.liebertpub.com/cms/10.1089/ars.2013.5566/asset/i... Here is a diagram of all the enzymes that need Tetrahydroibiopterin (BH4): https://www.researchgate.net/figure/Metabolic-pathway-of-BH4-dopamine-serotonin-and-tyrosine_fig3_322971717 https://www.researchgate.net/figure/Metabolic-pathway-of-BH4... NOS2 and the immune system: https://pubmed.ncbi.nlm.nih.gov/24477906/ https://pubmed.ncbi.nlm.nih.gov/24477906/ https://www.jimmunol.org/content/167/5/3000 https://www.jimmunol.org/content/167/5/3000 COVID and NOS2: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7754882/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7754882/ Zinc and hypertension: https://pubmed.ncbi.nlm.nih.gov/32090294/ https://pubmed.ncbi.nlm.nih.gov/32090294/ NOS3 uncoupling and hypertension: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4816601/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4816601/ NOS1 and psychosis: https://pubmed.ncbi.nlm.nih.gov/12140778/ https://pubmed.ncbi.nlm.nih.gov/12140778/ Zinc and Diabetes: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6984028/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6984028/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3407731/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3407731/ And the BIG one, Zinc and Heart Arrhythmia, you know the thing that all these your people are suddenly dying with? https://publichealth.jhu.edu/2022/covid-and-the-heart-it-spares-no-one https://publichealth.jhu.edu/2022/covid-and-the-heart-it-spa... https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7328074/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7328074/ You know, they are avoiding looking at zinc, purposefully, and I feel it is a crime against humanity. Seriously.
ThrowawayTestr 4y ago
This level of obsession over covid is not healthy.
thrown_22 4y ago
This thread is a perfect example of why normal people don't take obvious repercussions. The covid tangent is largely bullshit. You will get it regardless of what precausiosn you take. The point is that in a large number of venues we have CO2 levels that are actively detrimental to your ability to think. This is a problem that we need better ventilation to solve. That bedrooms had the poorest air quality is something I wasn't expecting and will likely buy my own sensor to measure.
jll29 4y ago
Thanks, great post. When you visit London, you should also measure your exposure to PM2.5, PM10, NO, NO2, ... - the risk of catching a virus is only one risk from your cocktails of risk types. https://eu.usatoday.com/story/news/world/2017/04/10/london-toxic-air-pollution-killing-thousands-every-year/100304958/ https://eu.usatoday.com/story/news/world/2017/04/10/london-t... https://www.london.gov.uk/press-releases/mayoral/londons-toxic-air-is-triggering-asthma-attacks https://www.london.gov.uk/press-releases/mayoral/londons-tox... https://www.unep.org/news-and-stories/press-release/revealed-every-londoner-exposed-dangerous-toxic-air-particles https://www.unep.org/news-and-stories/press-release/revealed...
Reason077 4y ago
> "Conclusions ... don't ride the buses is probably an early and obvious one." Yes, the air quality on London buses is consistently terrible on cold days. There is very little ventilation in those buses other than "open the windows", and when it gets cold people don't do that. Often it seems like you're not only breathing in everyone else's food smells and stinky breath, but road fumes and dust as well.
- dzhiurgis 4y ago
  Do brits also have “cold air and draft causes common cold” too?
  - Arbortheus 4y ago
    Yes, but it's something your grandparents might say rather than a widely held belief. I think people nowadays are clever enough to know that colds are a transmissible infection.
    - Reason077 4y ago
      Yeah. But most bus passengers still dislike being cold more than they dislike stale air. So most of the windows are usually closed.
      - MichaelCollins 4y ago
        CO2 clouds the mind and impairs judgement. Dressing inappropriately for the season is probably a symptom of this. People would dress more appropriately for the weather if they got more fresh air in the winter.
    - dzhiurgis 4y ago
      Typical response here is “but cold air weakens immunity“!
- Litost 4y ago
  It's also possible that air quality on the London Tube is much worse than the bus, at least for particulate matter: "Researchers found that a person travelling on a bus for two and a half hours was exposed to a third of what they would be travelling on the Tube for just an hour." https://www.independent.co.uk/news/uk/home-news/air-pollution-london-underground-tube-worse-than-above-ground-a8721586.html https://www.independent.co.uk/news/uk/home-news/air-pollutio... EDIT: Regarding CO2 levels, there's a 2018 FOI request which seems to imply it wasn't monitored back then, but was within regulatory limits though I'm not sure I'd want to travel on the tube more often than necessary? "The regulatory limits for CO2 are 5000 parts per million (ppm) for 8 hours time weighted equivalent or a short term exposure limit (15 minutes) of 15000ppm." https://tfl.gov.uk/corporate/transparency/freedom-of-information/foi-request-detail?referenceId=FOI-0540-1819 https://tfl.gov.uk/corporate/transparency/freedom-of-informa...
peteforde 4y ago
Two years ago, I was living in a house which I suspected had terrible air circulation, leading me to buy an Awair Element. It is not cheap - at $299, a small army of RasPi hoarders will dislocate their jaws, barking with with rage - but I genuinely love it. https://www.getawair.com/products/element https://www.getawair.com/products/element The immediate impact was that I became super nerdy about air quality, specifically CO2. It was indeed super high in that house; opening the window helped, but it led to me moving to a place with much better air quality in general. Nature in view, lots of green plants, and an HRV system. I can get <600ppm with the windows closed. TL;DR: if you ponder complex things for a living, you owe it to yourself to get nerdy about CO2 in your sleep and workspaces.
bloggie 4y ago
I wonder if he got COVID.
- lucb1e 4y ago
  Not all smokers get lung cancer, but I agree it would be funny if you appear so paranoid and then contract covid (though perhaps they have a legitimate reason to be particularly afraid of sars-cov-2, I don't know their age or comorbidities).
- pifm_guy 4y ago
  There are a bunch of other reasons to care about air quality... Like it being a proxy for your risk of a lot of other aborne pathogens (some of which, unlike COVID, you might actually permanently avoid, rather than COVID which is so infectious that measures like this might delay you getting it by a few days but probably not more as a varient sweeps through everyone in your city).
- hardaker 4y ago
  Nope. Not yet as of Monday, Nov 14th. [who just found this discussion of my article... which started long before I finished even getting all the data on the page]
  - hardaker 4y ago
    [further note: I'm pretty consistent about using an N95 mask at nearly all times when I'm not actively eating or drinking]
dzhiurgis 4y ago
I bought Qingping and it’s best and worst purchase at the same time. On one hand it proved you need to open windows frequently and it’s cool to monitor co2 in public places. On other hand it’s depressing good ventilation won’t happen for decades if not centuries and it’s unfeasible to open windows in super cold, hot or humid climates. Also, my measurements were different from author. On a plane co2 was pretty bad until AC was turned on (usually around midway boarding), then it hovered around 1000ppm. On a train it also stayed around 1000ppm.
NotYourLawyer 4y ago
CO2 levels are interesting in their own right. But imagine being a vaccinated person, wearing N95 masks, and still being this afraid of covid. Lose the mask and hire a therapist.
- lucb1e 4y ago
  You don't know their age, comorbidities, or what persons they live with that might be susceptible. Plus, I find it interesting from a technical standpoint as well. My current obsession is inflation but I simply enjoy tracking different supermarket product prices and seeing what it reveals more than that I actually need to save up for any particular goal. Tracking data is also a way to pass the time on journeys.
  - ThrowawayTestr 4y ago
    They're willing to attend a convention. Safe to assume they're not immunocompromised.
    - lucb1e 4y ago
      Either that or they're trying to live a normal life while dealing with it. You're probably right on that point, though note it was only one of the possibilities mentioned.
- pifm_guy 4y ago
  I would like to see an analysis of this... For example, how does wearing a mask every day impact lifetime infection risk? On one hand, masks are pretty effective at blocking pathogens. But on the other, as the rest of the population gets infected around you, your exposure to things you haven't yet seen will get really high, so it might turn out that wearing a mask 24*7 just delays your inevitable infection by a few days or weeks.
aaron695 4y ago
sampo 4y ago
> (it turns out my office really needs a fan as the single plant on the opposite side of the room is failing to keep up even with my sedentary exhaling) A human exhales about 1 kg of CO2 in a day (24 hours). That is about 270 grams of C. You'd need enough plants to sequester 270 grams of carbon, or about 0.5 kg of biomass (dry weight) per day, to "keep up" with your exhaling. This is much more than one houseplant.
- kragen 4y ago
  my notes from 02019 https://dercuano.github.io/notes/gardening-machines.html https://dercuano.github.io/notes/gardening-machines.html say that my rosemary bush had a doubling time of about 66 days rosemary is about 50% water [citation needed] and most of the dry part is carbohydrate, (ch₂o)ₙ, which should weigh [edited] 68% as much than the co₂, so roughly each kg of co₂ becomes 1.4 kg of rosemary a doubling time of 66 days is about 1.05% growth per day, so you need about 130 kg of rosemary bush in your office to grow 1.4 kg per day and thus keep up with your exhaling except actually it only needs to grow 1.4 kg per day during the daytime, not at night when it isn't photosynthesizing, so maybe you could get by with 90 kg of rosemary bush or so and probably about half a tonne of soil, say about 2 m² could be a single plant but it's kind of a tree-sized plant if you need it to suck up your co₂ at night you need a crassulacean acid metabolism (cam) plant like aloe, but i think you need a larger amount of it because cam plants tend to grow slower. maybe moringa but i don't know if it's obligate cam or facultative cam [edited to correct calculation erorr]
  - OJFord 4y ago
    > maybe you could get by with 90 kg of rosemary bush or so Which would be massive, and look absurd indoors. Though maybe that's not a problem, since you shouldn't have anyone over who might laugh at and embarrass you over it - it'd then be only half as big as it needs to be!
    - kragen 4y ago
      i think it would look freaking awesome and smell amazing. i would love it if this were the new standard for offices might harbor moths tho
bArray 4y ago
> I went 2.5 years with no plane fights and minimal in-person contact to suddenly "everyone must get back to normal! get on those planes! let's have lots of face to face meetings!" I don't know the author's background, but I really hate that otherwise normal people have been reduced to such measures. The advice to return to normal is good. 2.5 years of lockdown were mostly wasted - sorry, enjoy the resulting recession. If you are healthy, COVID is just a nasty flu. Take a few days off work, and go back knowing that your natural immunity will serve you well going forwards. One thing that doesn't appear to be addressed is that CO2 is a rough measure for potential exposure, but indoors the air circulation flow is really important. You want the air to take the longest possible path from another person before it meets you. Better yet through a filter, even better it never meets you at all.
- legulere 4y ago
  It’s a particularly nasty flu. You’re well advised to train your immune system before encountering the first time with vaccination. It also makes sense to reduce the dangers of infection (not just of Covid), as every infection also does lasting damage to your body including the immune system (there’s a really smart study about measles in the Netherlands about that). What you are doing is an optimization problem: you want to reduce your risk of getting infected while restricting yourself as few as possible. How restricting you find measures and how much you want to prevent getting infected is a very personal thing. I will wear masks while shopping and in public transportation, but I still go to restaurants (without masks). Other people will find masks too insufferable. Hand hygiene and air hygiene for new buildings should be a no-brainer though.
  - bArray 4y ago
    > It’s a particularly nasty flu. No doubt, but for the majority it is recoverable. > You’re well advised to train your immune system before encountering the first time with vaccination. I believe that it's effectiveness is greatly reduced now. The available vaccine was for the alpha variant. From what I remember reading, it essentially no longer reduces the probability of you getting COVID at all, meaning your immune system is essentially unprepared (and hence can't defend against it). > It also makes sense to reduce the dangers of infection (not just of Covid), [..] Somewhat, but then you never end up building natural immunity to anything. You have those isolated tribes that would likely get killed off by the common cold if it was ever introduced to them. > How restricting you find measures and how much you want to prevent getting infected is a very personal thing. It is a personal thing, but it was also an idea inflicted on people. This was not generally well practised before, nor does it particularly have any benefit done in small (read one) isolated pockets. I believe we have all now seen people who are many-times vaccinated, wear multiples masks, avoid any contact with people, and yet are otherwise perfectly healthy. > Hand hygiene and air hygiene for new buildings should be a no-brainer though. Even prior to COVID, I wish more consideration was put in place for air quality. Bin the ionizers and get decent filters in place that reduce carbon dioxide filters.
p1mrx 4y ago
I installed a Raspberry Pi with a CO2 sensor. When levels are high, it runs the bathroom exhaust fan to ventilate the house. Instructions and code at https://github.com/pmarks-net/exhale https://github.com/pmarks-net/exhale
simonebrunozzi 4y ago
This topic brings up one of the biggest issues I have: I couldn't find a single, reliable CO2 monitor that I could plug and play into my home or office. I tried PurpleAir, which seemed to be quite good in this regard; but then you read reviews and tests that compare multiple sensors in the same room, and you don't know what to believe.

183 points by zdw 4y ago

This seems to pretty well justify my recent approach to covid precautions which is to wear an N95 mask on public transport (and nowhere else), and to try and avoid social situations in densely packed rooms where practical.

MuffinFlavored 4y ago
does wearing a mask stop from spreading if you have it or stop you from getting it from others or both?
- Baeocystin 4y ago
  An N95 does both, to a highly effective degree.
  - deleted 4y ago
    [deleted]
  - timr 4y ago
    We have no good evidence for this claim. The only studies involving n95 masks and respiratory illness were conducted in hospital settings (i.e. don't reflect "normal" life), have high risk of bias (i.e. were small and were not randomized, controlled trials), and have shown mixed results. This is the WHO review that summarized the existing evidence for masks at the start of the pandemic. There were 4 studies on n95 masks in hospitals: https://www.thelancet.com/journals/lancet/article/PIIS0140-6 https://www.thelancet.com/journals/lancet/article/PIIS0140-6... Additionally, this is the most comprehensive review of mask literature I am aware of. It explicitly states that: > At least ten studies evaluate the clinical efficacy of different types of masks compared to one another, but without a no-mask control group most provide little insight into mask efficacy. > Four RCTs, four meta-analyses, and one prospective cohort study found surgical masks were non-inferior to N95s for protection against respiratory infections, and one found evidence that N95s provide greater protection than medical masks against self-reported clinical respiratory illness but not ILI. However, a recent review found that evidence that N95s protect healthcare workers from clinical respiratory infections at all is “low quality". One meta-analysis of particular note, an April 2020 preprint of a Cochrane review of clinical evidence for both surgical and N95 masks, “did not find any differences in the clinical effectiveness of either type of mask in the setting of respiratory viral infection transmission to healthcare workers,” although the review’s final November version omitted this language. https://www.cato.org/sites/cato.org/files/2021-11/working-paper-64.pdf https://www.cato.org/sites/cato.org/files/2021-11/working-pa... We simply don't know if n95 masks provide any protection -- personal or otherwise -- in the real world. That is the only honest answer to the parent's question. Everyone who claims otherwise is extrapolating from laboratory experiments, low-quality observational data, or (this is probably the most common) hearsay.
    - HyperSane 4y ago
      Why do surgeons wear masks?
      - MobiusHorizons 4y ago
        Not an expert, but as I understand it, surgeons could be exposed to much more than airborne viruses (bacteria, bodily fluids, etc). So masks would be worn for more possible reasons. It’s a good question though, I hope someone knowledgeable answers it.
        azakai 4y ago
        Surgical masks and face shields are indeed designed specifically to protect from fluids. That is very important too. Separately from that, when there is a risk of airborne transmission as there is with Covid, doctors and nurses will wear appropriate masks like N95s.
    - andbberger 4y ago
      nonsense, N95s are highly effective and if you want to make a good faith argument that they're not try citing the new england journal of medicine and not the fucking cato institute, good lord
      - deleted 4y ago
        [deleted]
    - azakai 4y ago
      > We simply don't know if n95 masks provide any protection -- personal or otherwise -- in the real world. That is simply not true. First, doctors and researchers consistently say that N95s are known to provide protection against Covid. Second, this is the first google result on that topic: https://www.cdc.gov/mmwr/volumes/71/wr/mm7106e1.htm https://www.cdc.gov/mmwr/volumes/71/wr/mm7106e1.htm Quoting from that CDC page: > What is already known about this topic? > Face masks or respirators (N95/KN95s) effectively filter virus-sized particles in laboratory settings. The real-world effectiveness of face coverings to prevent acquisition of SARS-CoV-2 infection has not been widely studied. > What is added by this report? > Consistent use of a face mask or respirator in indoor public settings was associated with lower odds of a positive SARS-CoV-2 test result (adjusted odds ratio = 0.44). Use of respirators with higher filtration capacity was associated with the most protection, compared with no mask use. > What are the implications for public health practice? > In addition to being up to date with recommended COVID-19 vaccinations, consistently wearing a comfortable, well-fitting face mask or respirator in indoor public settings protects against acquisition of SARS-CoV-2 infection; a respirator offers the best protection. You can say that that might be just correlation, but as those quotes mention, we do know how N95s work: they filter viral particles. That is easy to prove in lab settings. Real-world settings involve more factors, like how well-fitting the mask is, but it would be very surprising if a good N95 properly used did not offer any protection! N95 masks work. It's a good idea to wear one when relevant.
- VancouverMan 4y ago
  Some long-term, large-scale studies of the effects of widespread public masking have been performed recently. For example, one lasting over 1.5 years was done in the province of Ontario, Canada, involving approximately 15,000,000 participants, in environments ranging from dense urban settings to sparse rural ones. In Ontario's largest and densest population center, Toronto, the duration this study was about 2 years in length. It was conclusively demonstrated that widespread public masking does not prevent infection, and it does not prevent transmission, of airborne viruses. It was conclusively proven that such masking did cause accessibility problems, it did cause significant social disruption, and it did cause environmental damage, among numerous other harmful effects.
  - HyperSane 4y ago
    Can you provide a link to this study? If masks don't work then why do surgeons wear them?
    - samatman 4y ago
      To the latter question, it's to prevent droplets of spittle from landing on exposed tissue. There are pathogens which spread by droplets, rather than aerosols, the Sars2 virus doesn't happen to be one of them. Yes, if you spit directly onto an open wound or mucous tissue, but it doesn't live long on surfaces, and the droplet-fomite route is how that vector of infection works.
      - HyperSane 4y ago
        "prevent droplets of spittle from landing on exposed tissue" Isn't tiny droplets of saliva how most respiratory viruses spread?
    - lucb1e 4y ago
      They're joking that there were infections in the city despite mask requirements (surprise) and that mask requirements caused "significant social disruption".... At least I hope it's supposed to be a joke.

nicoburns 4y ago

Does anyone have any idea why CO2 levels would spike so high when a plane takes off?

pstrateman 4y ago
When planes take off there's often a strong smell of exhaust. Presumably the external air mix is just full of exhaust before they're at speed.
- pornel 4y ago
  Or perhaps external air intake is closed/limited because of the smell.
akira2501 4y ago
I'm not exactly sure, but during take off the "packs" are typically disabled. This removes air conditioning and probably lowers the amount of air that would be circulating when they are enabled.
- sokoloff 4y ago
  The air cycle machine (“packs”) are turned off if maximum power is needed (as their use requires bleed air, which takes power from the engine).
  - mleonhard 4y ago
    The author's DEN-LHR flight was on a Boeing 787 aircraft, which use electrically-powered air compressors [0]. They do not draw air from the engine. 787 maintain internal air pressure equivalent to 6,000 feet of elevation. All other commercial aircraft maintain 8,000 feet air pressure. I think most of my discomfort from long flights is due to altitude sickness. The only time I have slept on a long flight and awakened refreshed was on a 787. Jet engines use a neuro-toxic lubricant. Occasionally, some of this enters the cabin through the compressed air feed and poisons the passengers [1]. 787 passengers don't have this risk because the planes don't draw air from engines. [0] https://en.wikipedia.org/wiki/Boeing_787_Dreamliner#Interior https://en.wikipedia.org/wiki/Boeing_787_Dreamliner#Interior [1] https://pubmed.ncbi.nlm.nih.gov/24713335/ https://pubmed.ncbi.nlm.nih.gov/24713335/

jeroenhd 4y ago

One thing I wonder about, especially seeing the numbers during take-off: how well can an Aranet 4 sensor deal with changes in pressure and temperature? As I understand it, these sensors require (sometimes lengthy) calibration to remain accurate. For automatic calibration, the device needs to be in fresh air for 30 minutes, no closer than 1 meter from the nearest person. There is also a manual calibration method. I don't know how often calibration is necessary, but I also think this use case may not be what the sensor was designed to do.

phphphphp 4y ago
I think you might have it the wrong way round, as the product information mentions fresh air as a requirement for manual calibration, not automatic. "If a drift of the CO2 measurements occurs, calibration feature of the device should be used. Auto calibration mode is utilizing ABC algorithm whereas Manual calibration mode demands sensor to be exposed to fresh air." "CO2 sensor of the device is calibrated at standard atmospheric pressure. CO2 readings are pressure compensated and comply with the specifications down to 750 hPa. If the device has to be used at high altitude for a prolonged period of time, manual calibration of the unit should be performed for optimal performance. It is not intended to use the device higher than 4000 m (13 000 ft) above the sea level." https://cdn.bfldr.com/FS48XT6B/at/k9b9wjnv8f455crkp7846j/Aranet4_datasheet_v25_WEB.pdf https://cdn.bfldr.com/FS48XT6B/at/k9b9wjnv8f455crkp7846j/Ara...
mox1 4y ago
yea I recently started monitoring my homes CO2 levels with some DIY sensors. You need to enter your elevation above sea level or have a pressure sensor hooked up. So if the op set a static pressure I assume that would affect the readings a lot. Calibration is also just the sensor looking for the co2 floor (ie the lowest level possible). You need to do this weekly or monthly maybe..? Auto calibration just sets the lowest level it has recently seen as the floor.
- ahaucnx 4y ago
  What was your experience with the DIY monitor that you build? I am asking because we maintain an open source / open hardware indoor air quality project [1] that we continuously update and I am interested to learn about missing features we might have. Did your build have a dedicated pressure sensor? [1] https://www.airgradient.com/open-airgradient/kits/ https://www.airgradient.com/open-airgradient/kits/

djmips 4y ago

I have a few thoughts. One: that even if the C02 seems fine, if the din of the room means everyone is shouting then viral dispersal will be much higher. Two: it seems like having fresher air, will be more costly in the winter unless people can put up with lower temperature. I wonder how effective an airplane filter really is with regard to viruses. Should buildings and enclosed spaces be redesigned to include better filtering and at what running cost will that be?

kortilla 4y ago
> wonder how effective an airplane filter really is with regard to viruses. Airplanes are far better than any normal indoor building space. It’s a constant blend of outside air that means the entire cabin’s volume of air is gone within something like 5 mins.
- sampo 4y ago
  > Airplanes are far better than any normal indoor building space. But only when they fly. When you are waiting that 30 minutes sitting in the plane after boarding, the fraction of re-breathed air can get high. People have measured 2000 and 4000 ppm CO2 readings.
  - MichaelZuo 4y ago
    Looking from the chart it seems like the CO2 levels were elevated for the entire flight? As in it never dips below 1200pm on either the short haul or long haul flight. Also with the caveat in the article: "Note that the graphs below aren't calculated for altitude adjustment. Since planes are generally pressurized to an equivalent of 8000 feet, and senor drift is typically 3 per 1000 feet of elevation, it means that while in the air the CO2 levels are likely $24% higher than shown on the graph." It seems the logged numbers are underestimating it.
hedgehog 4y ago
On the energy item modern HVAC systems use a device called an ERV to greatly reduce energy loss to ventilation. No need to turn down the heat to get fresh air. The thermal plume associated with each occupant makes the problem a bit easier too, in general stale air heads to the top of the room because it's warmer and more humid therefore less dense. Not a new idea and some good models to look at. https://en.wikipedia.org/wiki/Energy_recovery_ventilation https://en.wikipedia.org/wiki/Energy_recovery_ventilation https://techxplore.com/news/2020-12-ventilation-easy-highly-effective-low-cost.html https://techxplore.com/news/2020-12-ventilation-easy-highly-... https://hackaday.com/2022/07/07/the-benefits-of-displacement-ventilation/ https://hackaday.com/2022/07/07/the-benefits-of-displacement...

thadk 4y ago

Several of us have built visualization tools which produce output a bit similar to the one in this article for the aranet4 unit. These can be found linked from: https://observablehq.com/@thadk/aranet4-explorer https://observablehq.com/@thadk/aranet4-explorer. Works best with the iPad app on an M1/M2 macOS computer. There are also several other ways to get the output such as a bleak project on GitHub (https://github.com/Anrijs/Aranet4-Python https://github.com/Anrijs/Aranet4-Python).

stuaxo 4y ago

I need to start using my Aranet 4, which case did you buy, I already dropped mine on the floor once and it felt lucky it didn't break.

MobiusHorizons 4y ago
Not the op, but it looked like the case that comes with Chinese iems (fancy earbuds)
- hardaker 4y ago
  I am the OP :-) It's actually a "CASEMATIX Portable Credit Card Reader Case Compatible with Square Contactless and Chip Reader, Case Only", which was the best possibility I could find. It would be nice if someone would make a dedicated case for the aranet4 as it is fairly sensitive. I'm fairly happy with this cheap case, but I'd like something that was better fit and designed for air intake, eg.

cobertos 4y ago

The anecdote about being sleepy on a plane makes me wonder if we couldn't just modulate our CO2 intake as a sleep aid. I find it _incredibly easy_ to sleep on a plane, and I generally have a very hard time with sleep due to brain not turning off. I think it would be interesting to see if there's any correlation between restful sleep and CO2 levels too. Maybe change the CO2 level to higher to induce sleep, and then fall asleep, and then bring it back down to have a nicer sleep.

avian 4y ago
I would hate to have a machine in my bedroom that is capable of raising the CO2 level. I don't think anyone could convince me that it would not decide to suffocate me at midnight next 29th February or something, regardless of its safety features.
- MobiusHorizons 4y ago
  I think the general idea would be to have a device that typically reduces co2 level through ventilation, and just turn it off at night. That would let your normal breathing add the co2.
  - lucb1e 4y ago
    I wouldn't like to take hours for my sleep aid to kick in, if I would need such a thing. Instead of the room, maybe a little device called blanket could be used, but I don't know how reliably people get out from under that if they get in the habit of associating under blanket = sleep = good, because it certainly wouldn't be good to be under that all night.
    - cobertos 4y ago
      Might help to have it on a schedule, like a thermostat has, or maybe more advanced like Nest does. Then it kind of tapers you into a sleep schedule. Wouldn't work if coming back from a late night out though
- 4y ago

dataflow 4y ago

I've heard some people can (train themselves to?) tell when the CO2 level rises in the room. Has anyone here managed to? If so, do you have any tips on how (or whether!) to do this, and/or what it feels like (if it's possible to give any vague explanation in text)?

zahrc 4y ago
It feels stuffy. I get headaches and get tired. When you open a window it’s almost like instant relief
- JohnBooty 4y ago
  Yeah the thing we've casually called "stuffy air" forever is, essentially, 100% equivalent with high CO2 levels. There are some other situations where non-"stuffy" air might have too much CO2, I guess. I guess you could pump CO2 into a room with cool, dry air. But barring a contrived situation like that, stuffy=CO2.
quakeguy 4y ago
That’s called grandpa-tells-you-to-go-sleep Syndrom, it is harmless usually.
afusalan 4y ago
> I've heard some people can (train themselves to?) tell when the CO2 level rises in the room. Has anyone here managed to? If so, do you have any tips on how (or whether!) to do this, and/or what it feels like (if it's possible to give any vague explanation in text)? The best indication is feeling sleepy. Once you become sleepy go outside and take deep breaths, then you understand the sensation difference between O2 and CO2.
- dataflow 4y ago
  Unfortunately that doesn't seem to work for me. Right now my room has > 1200ppm CO2 (due to closed doors/windows) but I don't feel sleepy at all, or any differently (that I can discern) from when it's < 600ppm. Do you know if it needs to be significantly higher for that feeling to kick in? If so, approximately how much?

ahaucnx 4y ago

We do indoor air quality monitoring and see very different results across buildings. The biggest differentiator is if the building has mechanical ventilation and to what extent this mechanical ventilation uses fresh air vs internal circulation. In unventilated crowded spaces like e.g. classrooms, we regularly see CO2 exceeding 3500 ppm. [1] However in classrooms with a well designed ventilation system you can keep the CO2 < 1000ppm during the whole school day. What the author did in his hotel room to turn on the fan or play around with the A/C settings is a good idea but many hotels Hvac systems do not draw in sufficient fresh air and you will see high CO2 developments. [1] https://www.airgradient.com/open-airgradient/blog/we-measured-the-co2-level-in-a-classrooms-this-is-what-we-found-out/ https://www.airgradient.com/open-airgradient/blog/we-measure...

icelancer 4y ago
3500ppm? That would imply an average CO2 level well above 1000ppm. No wonder why it's impossible to stay focused in lecture halls...
- MichaelZuo 4y ago
  Yeah, that really makes me rethink my entire education experience...
  - JohnBooty 4y ago
    ...you could always distract yourself by thinking about all of the political and military decisions that have been made throughout history, affecting millions and billions of human lives, in stuffy cramped rooms with excessively high CO2 levels. ...wait, that's not helping?
    - MichaelZuo 4y ago
      The utopia of adequate ventilation.
    - p1esk 4y ago

rufus_foreman 4y ago

I guess when I was born, background CO2 was around 330 ppm. Is there anything I can do to breathe air like that again in my house?

batch12 4y ago
Open a window?
- rufus_foreman 4y ago
  It's 420 ppm outside now.
- ad404b8a372f2b9 4y ago
  Background ppm is no longer at 330, so opening a window would not get you there. You would need to keep the window closed and remove more CO2 than you produce.
  - batch12 4y ago
    Fair point. I wonder if there is a big difference depending on where one lives. For instance, if one were to live in the country, surrounded by trees...
  - rufus_foreman 4y ago
    Yeah that's my question. How would I remove more CO2 than I produce. I've got the window closed, I have a few houseplants, and I am already considering getting rid of Mr. Tiddlesworth, my cat. Is there some sort of machine I can buy? Like direct air capture? I only need this in like two rooms of the house.
    - ad404b8a372f2b9 4y ago
      I don't think so. I guess what you want is a CO2 scrubber like they had in Apollo 13, but I don't know of any consumer, room-scale, ones. Plants make basically no difference sadly, in my room it gets to 1600ppm in under an hour just from me and my cat Gazpacho, although I've admonished him for breathing so much.

pfdietz 4y ago

That would be a worrying level of CO2 for the cockpit. https://www.newsweek.com/carbon-dioxide-levels-flight-deck-affect-airline-pilot-performance-1061068 https://www.newsweek.com/carbon-dioxide-levels-flight-deck-a...

Havoc 4y ago

Anybody know what the actual sensor inside that device is? Spec sheet doesn't seem to say

bloggie 4y ago
According to some quick duckduckgoogling for “aranet4 tear down” it could be this: https://senseair.com/products/power-counts/sunrise-hvac/ https://senseair.com/products/power-counts/sunrise-hvac/
- jobigoud 4y ago
  Yes, the Aranet 4 is even featured on the front page of SenseAir. "We're incredibly proud to have our CO2 sensor Senseair Sunrise inside this popular product." The sensor itself costs $229.00 at co2meter.com.

FollowingTheDao 4y ago

This is not going to change anytime soon. No one really cares about staying alive; climate change, diet, COVID. And COVID is now endemic and a pandemic. So either quit your job or learn about staying healthy when exposed to viruses that deplete zinc and other nutrients. Zinc deficiency lowers Tertrahydrobiopterin, which lowers coupled NOS, which lowers your immune system (NOS2) and gives you hypertension (NOS3) and makes you mental (NOS1). The Lower zinc also gives you diabetes. PubMed links for anyone who cares, but you probably don't.

stuaxo 4y ago
Please post the links, I feel like I live i a weird opposites world, where in the sane world we would have dealt with Covid by now, and have sorted out clean air in our public spaces (and to some extent homes too).
- FollowingTheDao 4y ago
  EDITIED TO ADD: Before taking Zinc get your Serum Zinc and RBC Zinc levels tested. Easy to do in the US if you have some money. Also get your Serum Copper and Ceruloplasmin tested since taking zinc at high dose for a while will lower copper since zinc creates Metallothioneins that capture the copper in the intestine before it can be absorbed. -- Hey, thanks for being curious! Science! Zinc and Tetrahydrobipoterin: https://pubmed.ncbi.nlm.nih.gov/31732151/ https://pubmed.ncbi.nlm.nih.gov/31732151/ The Gene GCH1 is central to making Tetrahydrobiopterin and uses zinc as a cofactor. https://www.uniprot.org/uniprotkb/P30793/entry https://www.uniprot.org/uniprotkb/P30793/entry The zinc coupling of NOS via GCH1: https://www.ahajournals.org/cms/asset/2cc8b7a0-a31a-4759-bc8d-da0d1f512dcf/7ff2.jpg https://www.ahajournals.org/cms/asset/2cc8b7a0-a31a-4759-bc8... Uncoupled NOS makes a lot of superoxides, BAD!: https://www.liebertpub.com/cms/10.1089/ars.2013.5566/asset/images/medium/figure5.gif https://www.liebertpub.com/cms/10.1089/ars.2013.5566/asset/i... Here is a diagram of all the enzymes that need Tetrahydroibiopterin (BH4): https://www.researchgate.net/figure/Metabolic-pathway-of-BH4-dopamine-serotonin-and-tyrosine_fig3_322971717 https://www.researchgate.net/figure/Metabolic-pathway-of-BH4... NOS2 and the immune system: https://pubmed.ncbi.nlm.nih.gov/24477906/ https://pubmed.ncbi.nlm.nih.gov/24477906/ https://www.jimmunol.org/content/167/5/3000 https://www.jimmunol.org/content/167/5/3000 COVID and NOS2: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7754882/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7754882/ Zinc and hypertension: https://pubmed.ncbi.nlm.nih.gov/32090294/ https://pubmed.ncbi.nlm.nih.gov/32090294/ NOS3 uncoupling and hypertension: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4816601/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4816601/ NOS1 and psychosis: https://pubmed.ncbi.nlm.nih.gov/12140778/ https://pubmed.ncbi.nlm.nih.gov/12140778/ Zinc and Diabetes: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6984028/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6984028/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3407731/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3407731/ And the BIG one, Zinc and Heart Arrhythmia, you know the thing that all these your people are suddenly dying with? https://publichealth.jhu.edu/2022/covid-and-the-heart-it-spares-no-one https://publichealth.jhu.edu/2022/covid-and-the-heart-it-spa... https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7328074/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7328074/ You know, they are avoiding looking at zinc, purposefully, and I feel it is a crime against humanity. Seriously.

ThrowawayTestr 4y ago

This level of obsession over covid is not healthy.

thrown_22 4y ago

This thread is a perfect example of why normal people don't take obvious repercussions. The covid tangent is largely bullshit. You will get it regardless of what precausiosn you take. The point is that in a large number of venues we have CO2 levels that are actively detrimental to your ability to think. This is a problem that we need better ventilation to solve. That bedrooms had the poorest air quality is something I wasn't expecting and will likely buy my own sensor to measure.

jll29 4y ago

Thanks, great post. When you visit London, you should also measure your exposure to PM2.5, PM10, NO, NO2, ... - the risk of catching a virus is only one risk from your cocktails of risk types. https://eu.usatoday.com/story/news/world/2017/04/10/london-toxic-air-pollution-killing-thousands-every-year/100304958/ https://eu.usatoday.com/story/news/world/2017/04/10/london-t... https://www.london.gov.uk/press-releases/mayoral/londons-toxic-air-is-triggering-asthma-attacks https://www.london.gov.uk/press-releases/mayoral/londons-tox... https://www.unep.org/news-and-stories/press-release/revealed-every-londoner-exposed-dangerous-toxic-air-particles https://www.unep.org/news-and-stories/press-release/revealed...

Reason077 4y ago

> "Conclusions ... don't ride the buses is probably an early and obvious one." Yes, the air quality on London buses is consistently terrible on cold days. There is very little ventilation in those buses other than "open the windows", and when it gets cold people don't do that. Often it seems like you're not only breathing in everyone else's food smells and stinky breath, but road fumes and dust as well.

dzhiurgis 4y ago
Do brits also have “cold air and draft causes common cold” too?
- Arbortheus 4y ago
  Yes, but it's something your grandparents might say rather than a widely held belief. I think people nowadays are clever enough to know that colds are a transmissible infection.
  - Reason077 4y ago
    Yeah. But most bus passengers still dislike being cold more than they dislike stale air. So most of the windows are usually closed.
    - MichaelCollins 4y ago
      CO2 clouds the mind and impairs judgement. Dressing inappropriately for the season is probably a symptom of this. People would dress more appropriately for the weather if they got more fresh air in the winter.
  - dzhiurgis 4y ago
    Typical response here is “but cold air weakens immunity“!
Litost 4y ago
It's also possible that air quality on the London Tube is much worse than the bus, at least for particulate matter: "Researchers found that a person travelling on a bus for two and a half hours was exposed to a third of what they would be travelling on the Tube for just an hour." https://www.independent.co.uk/news/uk/home-news/air-pollution-london-underground-tube-worse-than-above-ground-a8721586.html https://www.independent.co.uk/news/uk/home-news/air-pollutio... EDIT: Regarding CO2 levels, there's a 2018 FOI request which seems to imply it wasn't monitored back then, but was within regulatory limits though I'm not sure I'd want to travel on the tube more often than necessary? "The regulatory limits for CO2 are 5000 parts per million (ppm) for 8 hours time weighted equivalent or a short term exposure limit (15 minutes) of 15000ppm." https://tfl.gov.uk/corporate/transparency/freedom-of-information/foi-request-detail?referenceId=FOI-0540-1819 https://tfl.gov.uk/corporate/transparency/freedom-of-informa...

peteforde 4y ago

Two years ago, I was living in a house which I suspected had terrible air circulation, leading me to buy an Awair Element. It is not cheap - at $299, a small army of RasPi hoarders will dislocate their jaws, barking with with rage - but I genuinely love it. https://www.getawair.com/products/element https://www.getawair.com/products/element The immediate impact was that I became super nerdy about air quality, specifically CO2. It was indeed super high in that house; opening the window helped, but it led to me moving to a place with much better air quality in general. Nature in view, lots of green plants, and an HRV system. I can get <600ppm with the windows closed. TL;DR: if you ponder complex things for a living, you owe it to yourself to get nerdy about CO2 in your sleep and workspaces.

bloggie 4y ago

I wonder if he got COVID.

lucb1e 4y ago
Not all smokers get lung cancer, but I agree it would be funny if you appear so paranoid and then contract covid (though perhaps they have a legitimate reason to be particularly afraid of sars-cov-2, I don't know their age or comorbidities).
pifm_guy 4y ago
There are a bunch of other reasons to care about air quality... Like it being a proxy for your risk of a lot of other aborne pathogens (some of which, unlike COVID, you might actually permanently avoid, rather than COVID which is so infectious that measures like this might delay you getting it by a few days but probably not more as a varient sweeps through everyone in your city).
hardaker 4y ago
Nope. Not yet as of Monday, Nov 14th. [who just found this discussion of my article... which started long before I finished even getting all the data on the page]
- hardaker 4y ago
  [further note: I'm pretty consistent about using an N95 mask at nearly all times when I'm not actively eating or drinking]

dzhiurgis 4y ago

I bought Qingping and it’s best and worst purchase at the same time. On one hand it proved you need to open windows frequently and it’s cool to monitor co2 in public places. On other hand it’s depressing good ventilation won’t happen for decades if not centuries and it’s unfeasible to open windows in super cold, hot or humid climates. Also, my measurements were different from author. On a plane co2 was pretty bad until AC was turned on (usually around midway boarding), then it hovered around 1000ppm. On a train it also stayed around 1000ppm.

NotYourLawyer 4y ago

CO2 levels are interesting in their own right. But imagine being a vaccinated person, wearing N95 masks, and still being this afraid of covid. Lose the mask and hire a therapist.

lucb1e 4y ago
You don't know their age, comorbidities, or what persons they live with that might be susceptible. Plus, I find it interesting from a technical standpoint as well. My current obsession is inflation but I simply enjoy tracking different supermarket product prices and seeing what it reveals more than that I actually need to save up for any particular goal. Tracking data is also a way to pass the time on journeys.
- ThrowawayTestr 4y ago
  They're willing to attend a convention. Safe to assume they're not immunocompromised.
  - lucb1e 4y ago
    Either that or they're trying to live a normal life while dealing with it. You're probably right on that point, though note it was only one of the possibilities mentioned.
pifm_guy 4y ago
I would like to see an analysis of this... For example, how does wearing a mask every day impact lifetime infection risk? On one hand, masks are pretty effective at blocking pathogens. But on the other, as the rest of the population gets infected around you, your exposure to things you haven't yet seen will get really high, so it might turn out that wearing a mask 24*7 just delays your inevitable infection by a few days or weeks.

aaron695 4y ago

sampo 4y ago

> (it turns out my office really needs a fan as the single plant on the opposite side of the room is failing to keep up even with my sedentary exhaling) A human exhales about 1 kg of CO2 in a day (24 hours). That is about 270 grams of C. You'd need enough plants to sequester 270 grams of carbon, or about 0.5 kg of biomass (dry weight) per day, to "keep up" with your exhaling. This is much more than one houseplant.

kragen 4y ago
my notes from 02019 https://dercuano.github.io/notes/gardening-machines.html https://dercuano.github.io/notes/gardening-machines.html say that my rosemary bush had a doubling time of about 66 days rosemary is about 50% water [citation needed] and most of the dry part is carbohydrate, (ch₂o)ₙ, which should weigh [edited] 68% as much than the co₂, so roughly each kg of co₂ becomes 1.4 kg of rosemary a doubling time of 66 days is about 1.05% growth per day, so you need about 130 kg of rosemary bush in your office to grow 1.4 kg per day and thus keep up with your exhaling except actually it only needs to grow 1.4 kg per day during the daytime, not at night when it isn't photosynthesizing, so maybe you could get by with 90 kg of rosemary bush or so and probably about half a tonne of soil, say about 2 m² could be a single plant but it's kind of a tree-sized plant if you need it to suck up your co₂ at night you need a crassulacean acid metabolism (cam) plant like aloe, but i think you need a larger amount of it because cam plants tend to grow slower. maybe moringa but i don't know if it's obligate cam or facultative cam [edited to correct calculation erorr]
- OJFord 4y ago
  > maybe you could get by with 90 kg of rosemary bush or so Which would be massive, and look absurd indoors. Though maybe that's not a problem, since you shouldn't have anyone over who might laugh at and embarrass you over it - it'd then be only half as big as it needs to be!
  - kragen 4y ago
    i think it would look freaking awesome and smell amazing. i would love it if this were the new standard for offices might harbor moths tho

bArray 4y ago

> I went 2.5 years with no plane fights and minimal in-person contact to suddenly "everyone must get back to normal! get on those planes! let's have lots of face to face meetings!" I don't know the author's background, but I really hate that otherwise normal people have been reduced to such measures. The advice to return to normal is good. 2.5 years of lockdown were mostly wasted - sorry, enjoy the resulting recession. If you are healthy, COVID is just a nasty flu. Take a few days off work, and go back knowing that your natural immunity will serve you well going forwards. One thing that doesn't appear to be addressed is that CO2 is a rough measure for potential exposure, but indoors the air circulation flow is really important. You want the air to take the longest possible path from another person before it meets you. Better yet through a filter, even better it never meets you at all.

legulere 4y ago
It’s a particularly nasty flu. You’re well advised to train your immune system before encountering the first time with vaccination. It also makes sense to reduce the dangers of infection (not just of Covid), as every infection also does lasting damage to your body including the immune system (there’s a really smart study about measles in the Netherlands about that). What you are doing is an optimization problem: you want to reduce your risk of getting infected while restricting yourself as few as possible. How restricting you find measures and how much you want to prevent getting infected is a very personal thing. I will wear masks while shopping and in public transportation, but I still go to restaurants (without masks). Other people will find masks too insufferable. Hand hygiene and air hygiene for new buildings should be a no-brainer though.
- bArray 4y ago
  > It’s a particularly nasty flu. No doubt, but for the majority it is recoverable. > You’re well advised to train your immune system before encountering the first time with vaccination. I believe that it's effectiveness is greatly reduced now. The available vaccine was for the alpha variant. From what I remember reading, it essentially no longer reduces the probability of you getting COVID at all, meaning your immune system is essentially unprepared (and hence can't defend against it). > It also makes sense to reduce the dangers of infection (not just of Covid), [..] Somewhat, but then you never end up building natural immunity to anything. You have those isolated tribes that would likely get killed off by the common cold if it was ever introduced to them. > How restricting you find measures and how much you want to prevent getting infected is a very personal thing. It is a personal thing, but it was also an idea inflicted on people. This was not generally well practised before, nor does it particularly have any benefit done in small (read one) isolated pockets. I believe we have all now seen people who are many-times vaccinated, wear multiples masks, avoid any contact with people, and yet are otherwise perfectly healthy. > Hand hygiene and air hygiene for new buildings should be a no-brainer though. Even prior to COVID, I wish more consideration was put in place for air quality. Bin the ionizers and get decent filters in place that reduce carbon dioxide filters.

p1mrx 4y ago

I installed a Raspberry Pi with a CO2 sensor. When levels are high, it runs the bathroom exhaust fan to ventilate the house. Instructions and code at https://github.com/pmarks-net/exhale https://github.com/pmarks-net/exhale

simonebrunozzi 4y ago

This topic brings up one of the biggest issues I have: I couldn't find a single, reliable CO2 monitor that I could plug and play into my home or office. I tried PurpleAir, which seemed to be quite good in this regard; but then you read reviews and tests that compare multiple sensors in the same room, and you don't know what to believe.