[HN Gopher] A paradigm shift to combat indoor respiratory infection
___________________________________________________________________
A paradigm shift to combat indoor respiratory infection
Author : edward
Score : 136 points
Date : 2021-05-14 06:36 UTC (16 hours ago)
(HTM) web link (drive.google.com)
(TXT) w3m dump (drive.google.com)
| breck wrote:
| What a good read. Shame on the authors for putting such an
| important article behind a paywall. Thanks someone for
| filesharing it.
|
| #AbolishCopyrights #AbolishPatents #EndIntellectualStupidity
| N5Air wrote:
| At https://n5air.com/ we are formulating a quantitative "VIRUS
| INFECTION THRESHOLD" theory while fully recognizing it may
| already exist. Any leads? Also, is there a way to share its
| outline in a PDF file? Lev
| renaudg wrote:
| Here's a fascinating Twitter thread about the history of aerosol
| transmission denial in the medical community, going back to the
| early 20th century :
|
| https://twitter.com/jljcolorado/status/1391111720526024708?s...
| (It's 100 tweets long, here's a more readable version :
| https://threadreaderapp.com/thread/1391111720526024708.html)
|
| The tl;dr is that 20th century health authorities went too far in
| their rejection of the 19th century "miasma" theory of disease
| transmission, and now the pendulum is swinging back again.
| prof-dr-ir wrote:
| From the article: "It is not known exactly what fraction of
| infections could be prevented if all building and transport
| ventilation systems on the planet were ideal (in terms of
| controlling airborne infections), or the cost of design and
| retrofitting to make them ideal."
|
| I think this is the key question. Surely better ventilation would
| have prevented some infections in the covid pandemic. But how
| many? And to decide that we need not just manifestos by civil
| engineers (like this article) but convincing research results,
| probably in collaboration with people who actually know some
| things about viruses as well. And without it, could organizations
| like the WHO or CDC have plausibly recommended building upgrades?
| CoastalCoder wrote:
| I agree. Changing the building codes' ventilation requirements
| will cost time and money. And the resulting designs are
| potentially louder, bulkier, and less energy-efficient.
|
| Hopefully we'll make those changes if and only if doing so
| brings significant health benefits.
| radu_floricica wrote:
| It's the theoretical key question. The practical one is more
| like "how's the cost benefit curve looking like, especially in
| the beginning?".
|
| My personal completely unscientific musings on the topic ended
| with buying and cutting up a couple of vacuum cleaner hepa
| filters, thus obtaining a shocking quantity of filter cloth,
| which then can simply be taped over the standard AC mesh
| filter. AFAIK, "hepa" ACs don't even cover the full surface -
| they just have a patch of hepa, which just ensures the air
| inside gets circulated through it eventually - being
| recirculated, there's not that much of a hurry. I'd recommend
| low-end filters, you don't want to remove virus particles but
| much larger clusters of virus+saliva.
|
| So personally I'm guessing a rather high impact for very low
| cost / low effort changes.
| zargon wrote:
| The WHO and CDC have had their head in the sand for 60 years
| when it comes to airborne pathogens. They have only
| acknowledged aerosol transmission of covid in the last couple
| weeks. It was physicists who had to figure out why they were
| domatically denying reality. https://www.wired.com/story/the-
| teeny-tiny-scientific-screwu...
| SideburnsOfDoom wrote:
| This seems closely related, actually:
|
| Wired: EARLY ONE MORNING, Linsey Marr...
|
| OP article: A paradigm shift to combat indoor respiratory
| infection ... Linsey C. Marr (in the author list)
|
| Wired: . At one point, Lidia Morawska,
|
| OP Article: Lidia Morawska (first listed author)
| renaudg wrote:
| Here's a fascinating Twitter thread about the history of
| aerosol transmission denial, going back to the early 20th
| century :
|
| https://twitter.com/jljcolorado/status/1391111720526024708?s.
| ..
|
| It's 100 tweets long, may be more readable here :
| https://threadreaderapp.com/thread/1391111720526024708.html
| [deleted]
| ddxxdd wrote:
| Apparently the CDC has yet to catch up to 19th century
| physics.
|
| The physics of small particles moving in the air ("Brownian
| motion") was completely figured out by Einstein back in 1905.
|
| Given a virus' size and weight, it should be trivial for a
| physics graduate student to simulate how long it will be
| airborne.
| Izkata wrote:
| Per that Wired article, it was intentionally ignored when
| the first virus-related research came up in the 1940s
| because it was too close to the discredited miasma theory.
|
| > Given a virus' size and weight, it should be trivial for
| a physics graduate student to simulate how long it will be
| airborne.
|
| This is also in the article, known research from decades
| ago. Social distancing is in fact based on a
| misunderstanding and conflation of a few things in that
| early research.
| sandworm101 wrote:
| >> Given a virus' size and weight, it should be trivial for
| a physics graduate student to simulate how long it will be
| airborne.
|
| How long it remains airborne is beside the point. Does that
| physics grad know how long/if the virus can survive once it
| dries up? Do they know how long it will survive exposure to
| light? Do then know whether the virus can cling to dust
| particles?
|
| Even brownian motion is only half the story. Does the
| physics grad understand airflow in office spaces? Do they
| understand how fast air moves when a person coughs? How
| much turbulence is caused by opening an office door? Plenty
| of things can stay airborne for extended periods because of
| aerodynamics without regard to brownian motion
| (snow/rain/dust/salt etc). That physics grad better come
| with minors in aerodynamics, kinesiology, microbiology ...
| even some basic meteorology would be helpful.
| Enginerrrd wrote:
| As an civil / environmental engineer, I can assure you
| that particle size and average settling time is
| INCREDIBLY important to consider and will cover basically
| all of your supposed edge cases to the point of being
| statistically irrelevant. You would handle those edge
| cases by simply including a safety factor in the required
| residence time of the average particle within the system
| considered (or equivalently, you'd specify a certain log
| removal of pathogens). The end result of all your edge
| cases that you seem to think are so important is
| something like: "Ok, 1 in 100,000 may still get sick with
| this design. Good enough."
|
| You can make the same arguments for drinking water, and
| yet, as long as you follow the rules, it is unbelievably
| safe, despite the fact that no one gave a shit about
| turbulence along the baffles in the treatment tank.
| techdragon wrote:
| The thing about medicine is they like to test. Theory and
| simulation are nice but it's just not medicine and
| therefore not suitable for a doctor to tell to someone as
| "medical advice" with all of the _legal burden of
| malpractice_ that the term entails. "What if I'm wrong?" is
| a question that keeps good doctors awake at night and bad
| doctors have forgotten to ask themselves... when this kind
| of question weighs on you, it's natural human behaviour to
| become more cautious, to become risk averse and question
| the validity of newly presented information due to the
| potential that regardless of if their current understanding
| is wrong, there's no inherent guarantee that the new
| information is any less wrong.
|
| And so medicine is understandably a slow moving science,
| and the practice of medicine moves even slower as it
| represents the slow filtration of the cutting edge of
| medicine the science, through a complex web of human
| interaction. Which with a dash of "social capital" theory,
| makes it easy to see why we have unfortunately often
| ignored sound advice like this. The mistaken assumptions of
| people viewing a person who's expertise bridges two
| disparate fields, as being unable to understand things as
| deeply, clearly or fully, as the people dedicated to just
| one of those fields.
| svantana wrote:
| I can see your point, but isn't the WHO tweeting "FACT:
| #COVID19 is NOT airborne." an example of the opposite?
| They made a hard assertion without any clear proof to
| back it up.
| taxicabjesus wrote:
| Hmm? interesting. Here's the offending tweet:
| FACT: #COVID19 is NOT airborne. The
| #coronavirus is mainly transmitted through droplets
| generated when an infected person coughs, sneezes or
| speaks. To protect yourself: -keep 1m
| distance from others -disinfect surfaces frequently
| -wash/rub your hands -avoid touching your Eyes Nose
| Mouth
|
| - https://twitter.com/who/status/1243972193169616898
|
| The WHO gave a lot of bad advice. Some say that it was
| intentionally misleading. Promoting ventilation as a
| reasonable treatment for the initial stages of covid-19
| was the worst possible advice to give front-line medical
| practitioners who didn't know what they were dealing
| with.
|
| We now know that the fecal-aerosol route of transmission
| is very important. Forbes has a recent piece about the
| fecal-oral/aerosol route: https://www.forbes.com/sites/wi
| lliamhaseltine/2021/03/22/pre... Another tweet by ...
| someone was about how the masks effectively aerosolize
| droplets.
|
| Keeping bathrooms open but requiring face coverings was
| an exercise in futility.
|
| In the case of COVID-19, the WHO seems to have
| implemented #PrasadsLaw [0]. "Prasad's Law: Medical goods
| and services that concentrate wealth can be paid for;
| medical goods and services that disperse wealth are
| "unaffordable.""
|
| [0] https://news.ycombinator.com/item?id=21728864
| rhodozelia wrote:
| Farts are deadly now?
| loopz wrote:
| Good to expose such expert arrogance.
| jxramos wrote:
| that's fascinating, are CDC and WHO officials even practicing
| physicians? Would that have helped any?
| newsbinator wrote:
| > EARLY ONE MORNING, Linsey Marr tiptoed to her dining room
| table, slipped on a headset, and fired up Zoom. On her
| computer screen, dozens of familiar faces began to appear.
| She also saw a few people she didn't know
|
| It's really hard for me to read a WIRED article for
| information.
|
| I mean I realize that's not what it's there for but it takes
| forever to get into the content of the article.
| [deleted]
| inanutshellus wrote:
| Wait, is this a Wired link? The URL seems to go to
| drive.google.com and... that weirded me out so I didn't
| click on it but figured I'd check out the comments to see
| what folk had learnt.
| [deleted]
| 0xffff2 wrote:
| I refuse to click on Wired links anymore. The signal to
| noise ratio is way to low to ever be worth it.
| newsbinator wrote:
| Could someone here please make a Wired auto-summarizer
| that cuts out the stuff about what the subject of the
| article had for breakfast that day and retains the
| insights?
| c7DJTLrn wrote:
| Nails on chalkboard.
| vishnugupta wrote:
| > When the call ended, Marr sat back heavily, feeling an
| old frustration coiling tighter in her body. She itched to
| go for a run, to pound it out footfall by footfall into the
| pavement
| bsenftner wrote:
| This style of writing is so present tense
| sensationalized, I cease to believe what is written
| simply because all this fictionalized present tense prose
| they dress the article up is 100% made up - so how is one
| to take the "facts" seriously?
| weaksauce wrote:
| The short of it is that there was some early research done
| in TB transmission and they found that the nose was really
| good at blocking particles larger than 5 microns but it
| showed that 100 micron particles would be suspended in the
| air as an aerosol and there was subsequent research that
| used the 5 microns as gospel for aerosol cutoff even though
| particles greater than that could be considered aerosol and
| that cutoff stuck.
| bellyfullofbac wrote:
| Hear hear. Maybe Wired should talk about the coffee she's
| sipping, made from beans harvested on the south coast of
| Java, where there is a legend of a queen who drowned...
| andi999 wrote:
| I need more detail... what happened to the queens
| relatives.
| K0balt wrote:
| Forget the relatives, where did those BUTONS on her shoes
| come from!
| tengbretson wrote:
| The important thing was that she had an onion on her
| belt, which was the style at the time.
|
| Now, to take the ferry cost a nickel, and in those days,
| nickels had pictures of bumblebees on 'em. Give me five
| bees for a quarter, you'd say.
| wffurr wrote:
| Writers with frustrated literary ambitions...
| Reason077 wrote:
| > _" it takes forever to get into the content of the
| article."_
|
| I've found this is the style of American long-format
| journalism in general. Just look at something like The New
| Yorker: not to dispute the quality of their writing, but
| the word counts certainly skew high. Articles in comparable
| British publications tend to be a lot more succinct.
| e17 wrote:
| I agree, and if you consider Private Eye in particular,
| they make the New Yorker or The Atlantic look like the
| Proust. Having said that, the British periodical
| landscape is sorely lacking a good centrist/apolitical
| current affairs publication in the American style.
| auxym wrote:
| The Economist? Or do you consider that too right leaning?
| malandrew wrote:
| The Economist hasn't been right leaning for at least half
| a decade or longer now.
| renewiltord wrote:
| This is actually because of a cargo cult fetishization of
| longer texts. As most people moved to rapid consumption
| of many disjoint sound bites, knowledgeable people read
| more than headlines. Those who then wished to emulate
| these decided that anything long is meaningful leading to
| a fetishization of "long form" prose.
|
| You'll see a pretty high correlation between fans of
| "long form", readers of The Atlantic and The New Yorker,
| and political inclination around being perceived as
| erudite.
|
| It's one of those cargo cult mixed with a measure
| becoming a target.
| MaxBarraclough wrote:
| > Articles in comparable British publications tend to be
| a lot more succinct.
|
| Here's a counterexample literary trainwreck from the BBC.
| Have a go at wading through this horror show. It appears
| to have been written deliberately to withhold the topic
| of the article from the reader, for as long as possible.
| The wholly uninformative title is just the beginning.
| Those with the necessary patience will eventually realise
| that the title is also plainly untrue.
|
| https://www.bbc.co.uk/news/world-australia-49012771
| Angostura wrote:
| Again, this is a feature story, not a news story.
| SamBam wrote:
| I love The New Yorker. I actually read several pages of
| it every night to my wife to help her fall asleep. And
| that's not actually a joke about it being boring.
| (Currently reading about the evidence for UFOs, it's
| highly interesting.)
|
| However, almost every article follows such a predictable
| format: Introductory section, full of all the interesting
| and tantalizing details, and stuff you actually want to
| find out about. Then section two: we jump back to the
| main subject's childhood, what clothes they were wearing
| when the journalist met up with them, how softly they
| speak. About two pages of biographical content. Section
| 3: we jump to the background of the story we're actually
| going to tell. Explain how it fits into the history of
| some movement or scientific question or whatever. The
| "point" of the article gets buried somewhere in sections
| 4 or 5, in between riffing on other people's dead ends
| and more biographical content.
| dorfsmay wrote:
| I know this is going to sound crazy, but give it a try
| sometime.
|
| When I lose track while reading an article, or find
| difficult to understand it, I stop and reading it bottom
| up, one paragraph at a time. First the last paragraph,
| then the one before that, etc...
|
| This cuts through directly to the conclusion, then the
| detailed explanations form particular to general (which
| works better for me) and I can skip the "excitement build
| up" at the top of the article.
| vishnugupta wrote:
| I second this.
|
| I applied it to this[1] super long winded article in New
| Yorker to get the gist of the article. This article is
| littered with these passages and it's super frustrating.
| In the end from my view point it's a shallow piece with
| very little new insights. FWIW the article didn't age
| well as India is being ravaged by the 2nd wave.
|
| [1] https://www.newyorker.com/magazine/2021/03/01/why-
| does-the-p...
| saurik wrote:
| The New Yorker is a magazine, not a newspaper: it doesn't
| exist to quickly present information every day, but to
| provide entertaining writing once a month; reading it
| backwards to try to get to the point as fast as possible
| sounds as silly as doing the same to a movie or a book.
| throwawayboise wrote:
| Sounds like the recommended way to read a research paper:
| (1) read the abstract; (2) if you're still interested,
| read the conclusion; (3) if you're still interested, read
| the body of the paper.
| pbronez wrote:
| man... this is exactly the opposite of how news articles
| are supposed to be written.
|
| Good news articles should tell you everything in the
| headline. Then tell you everything again in the first
| body sentence. Then tell you everything again in the
| first paragraph. and the first page. And so on.
|
| It's supposed to be a fractal that unfolds additional
| detail as you press forward, while ensuring that even a
| casual reader comes away with a mostly complete and
| accurate understanding of the issue.
|
| More of THAT please.
| yboris wrote:
| I suspect that doing the opposite helps trap people on
| the page, resulting in more money going to advertisers.
| If all the info is at the top, who will scroll lower (and
| see more ads)?
| TeMPOraL wrote:
| Yeah, it's called "inverted pyramid", and it's supposed
| to be the gold standard of journalistic writing. IIRC
| it's being taught as part of vocational education.
|
| And yet, news media are the _last_ place you 're likely
| to find articles written in this style. Somehow, they
| manage to deliver the _exact opposite_ of what they
| should be. A fractal of confusion, recursively unfolding
| noise.
|
| (It's as if they were making a lot of money on maximizing
| the time a reader is engaged with any given article. It's
| as if - and I know this sounds crazy - the articles were
| there just to hold the user down, while they're being
| exposed to _something else_...)
| rcoveson wrote:
| > Yeah, it's called "inverted pyramid"...
|
| Narrow (succinct) at the top and broad (detailed) at the
| bottom seems like a normal pyramid to me.
|
| An "inverted pyramid" would be like one of those poems
| that describes fine details first and only in the last
| sentence reveals what it's been describing.
|
| I don't doubt that it's actually called that, but it
| seems backwards to me.
| Angostura wrote:
| Yeh, it's simply called pyramid structure.
| Angostura wrote:
| Its 'pyramid structure', not inverted. It was used in
| newspapers for two reasons.
|
| The first is because, yes it allows busy readers to
| access the most salient facts first. But secondly, and
| perhaps more importantly from the point of print
| newspaper production, it allowed subs to always cut from
| the bottom, without having to read the whole piece
| carefully...
|
| Newspapers would go through several editions throughout
| the night as new stories came in or existing stories were
| expanded. What started life as a front page lead might
| find itself moved to page three and progressively
| shortened, possibly down to a 1 sentence news-in-brief
| NIB.
|
| The pyramid style let subs always fit a story into the
| available space, simply by cutting everything
| progressively from the bottom.
|
| This story in Wired is _not_ a news story and is not
| written as a news story. It is a feature story and its
| construction follows different rules.
|
| It's a very good feature story, in my opinion.
| saurik wrote:
| Wired is a magazine, not a newspaper: it doesn't exist to
| quickly present information every day, but to provide
| entertaining writing once a month; insisting it use an
| inverted pyramid is as strange as arguing that if only
| movies and books just led with the resolution, it would
| save you a lot of time.
| jerf wrote:
| "this is exactly the opposite of how news articles are
| supposed to be written."
|
| I'm not accusing you of doing this on purpose, but
| there's a certain amount of equivocation in the phrase
| "news article" there. Yes, that's a style that is
| recommended for factual news articles in a newspaper
| context, but that's not the only form of "news article".
|
| Call this a "news essay" instead and give it its own
| style and it might make more sense. It's been around for
| a long time. Could call it the 20th-century equivalent of
| clickbait and probably not be far off.
|
| "There's an exciting revolutionary change to physics
| coming... but first, the full life story of the thesis
| advisor's influential father... keep reading...."
|
| Arguably it's more a form of entertainment than
| information.
| hobs wrote:
| Sure, but most of the content they are writing is neither
| entertaining or engaging, its long and wandering and I
| couldn't care less.
|
| No novel is allowed to lollygag around the point its
| trying to achieve in the way these articles flagrantly
| waste your time.
|
| It's like someone misunderstood that the act of moving
| your eyes along the page is not interesting in and of
| itself.
| PaulDavisThe1st wrote:
| >No novel is allowed to lollygag around the point its
| trying to achieve in the way these articles flagrantly
| waste your time.
|
| With barely less than a second's though: Watership Down,
| a hugely popular novel in the 1970s, spends untold
| amounts of text/paper immersed in detailed descriptions
| of the flora that the characters are moving through or
| eating.
|
| Why not just say "I don't enjoy this style of writing",
| rather than trying to come up with some supposedly
| objective metrics for how other people should write?
| [deleted]
| SideburnsOfDoom wrote:
| I have read both now, and IMHO there's more actual content
| about scientific matters in the Wired piece.
| heisenbit wrote:
| A considerable number of deaths could be prevented. There are
| models that show that masks helped to curb spread of flu so
| well that excess deaths due to Covid in some places became
| negative.
| ur-whale wrote:
| There is a "law of unintended effects" question as well: if we
| were to live - and presumably grow up - in such a sanitized
| environment, what would happen to our immune system.
|
| There's a sizeable chance it would be extremely weak and that'd
| we'd be incapable of resisting many disease on our own and
| therefore would become completely dependent on the air cleaning
| infrastructure.
| f6v wrote:
| You still eat fresh fruits and vegetables, touch the surfaces
| on your way to work etc. There're countless pathogens
| everywhere. So I guess we would be fine?
|
| You're right that our immune system didn't evolve to be in a
| sterile environment. But we also weren't meant to be that
| close to that many humans.
| ur-whale wrote:
| >So I guess we would be fine?
|
| Can you catch airborne respiratory diseases from eating
| fruit?
|
| What I'm saying is: we run the risk of never being able to
| go outside again if we eliminate all airborne pathogens.
| falseprofit wrote:
| Are you suggesting that bringing more air from outdoors
| into our indoors environments will cause us to lose our
| ability to tolerate outdoors air?
| f6v wrote:
| > Can you catch airborne respiratory diseases from eating
| fruit?
|
| I'm willing to speculate that exposing our immune system
| to surface pathogens helps deal with airborne pathogens.
| Enginerrrd wrote:
| Not to worry, people will still have children, and I
| assure you, they'll still go out into the world and lick
| the doorknobs/each other and get you sick so you can
| bring it to work.
| daniellarusso wrote:
| This is the Ben Franklin / John Adams debate when they shared a
| small room together overnight with one window.
|
| "When Adams explained that he didn't want to catch an illness
| from the cold night air, Franklin countered that the air in
| their room was even worse."
|
| https://www.mentalfloss.com/article/54169/time-ben-franklin-...
| Joker_vD wrote:
| Miasma theory rears its ugly head once again: https://en.wiki
| pedia.org/wiki/Miasma_theory#Contagionism_ver...
|
| The night air is dangerous, close those windows before you go
| to sleep!
| goldenkey wrote:
| Miasma was a perfectly good theory and if anything, is
| obviously true innately. Bad smelling air from urine, shit,
| festering corpses and the like, was often laden with
| viruses, bacteria, and noxious chemical fumes. Sure, plenty
| of diseases are not airborne but air that smells like shit
| isn't exactly a boon to be inhaling. There is a non zero
| chance of getting sick from noxious air.
| Joker_vD wrote:
| Yes, it's "obviously true" because of the confounding
| factors: bad air tends to go hand in hand with dirty
| water, contaminated food, and infection-carrying insects.
|
| Neither cholera, malaria, typhoid nor plague are
| airborne, and yet their causes were ascribed to miasmata.
| goldenkey wrote:
| Right but the metabolites produced by the bacteria are
| harmful in their own right. And let's be clear, there are
| many airborne contagions like the common cold that
| haven't been indexed through the centuries. It isn't a
| good idea to inhale shit air for days on end, just like
| it isn't a good idea to inhale car fumes for days on end.
|
| https://en.wikipedia.org/wiki/Volatile_organic_compound
| nradov wrote:
| Nonsense. The pathogens in urine, shit, and corpses are
| almost never airborne. And the fumes are only toxic in
| extremely high concentrations. The chance of getting sick
| is effectively zero.
| goldenkey wrote:
| Nonsense. The risk is nonzero. Turbid air takes a toll
| both physically and mentally, and can lead to
| inflammation and weakening of the body's defenses. Your
| definition of sick is quite narrow.
|
| https://en.wikipedia.org/wiki/Volatile_organic_compound
| nradov wrote:
| No you're just making things up. The link you posted
| doesn't support your statement.
| yosito wrote:
| This reminds me of an argument I had with a friend in
| October. When the weather got cold, I only wanted to
| socialize with our small group of friends outside because the
| open air was safer, but she only wanted to socialize inside
| because she thought being outside in the cold would make her
| catch COVID.
| londons_explore wrote:
| I would put money on COVID not happening at all if all
| buildings had 10 air refreshes per hour, and that air either
| coming from the outdoors or going through a HEPA filter.
|
| I would guess an analysis of workplace COVID rates would see a
| strong correlation between workplaces with and without
| filtration in their AC systems.
| sjg007 wrote:
| Well the spanish flu happened and they did not have HVACs
| back then and all the windows leaked.
| x3iv130f wrote:
| Spanish Flu is a really bad name for this disease.
|
| From what we know it started in Kansas. It should be called
| 1918 Flu Pandemic.
| dragonwriter wrote:
| It's called Spanish Flu because Spain was the first
| country not to cover it up to avoid adverse morale
| effects and revealing potential weakness because of WWI.
| hasmanean wrote:
| There's a saying, earthquakes don't kill people--buildings
| kill people when they collapse.
|
| In the open air on a grassland, covid won't kill a
| population. The design of our hermetically sealed buildings
| is what's killing us.
|
| Back in the 1970s the air outside was full of lead and smog,
| so the safest thing too was completely seal all office
| buildings.
|
| Today the air inside probably contains more hydrocarbons
| (from volatile organic compounds offgassing from carpets and
| furniture) so the best thing to do is vent air to the outside
| and keep the windows open (assuming you live in a mild
| climate)
|
| Of course, that flies in the face of all efforts to make
| things green...which involve better insulation, sealing
| windows against leaks, more air filtration systems and etc.
|
| Here in Canada the temperature drops like 5 or 10 degrees
| when you walk into a forest. I've stepped into a traditional
| mud hut and experienced a similar cooling effect. The common
| denominator is that both environments have a high surface
| area compared to say concrete. This acts as an efficient
| radiator so that when water to evaporates it removes heat. In
| low humidity climates this is one way to reduce cooling
| demands. Beyond that if we cool micro zones or interstate
| cooling into clothing itself through hoses or something that
| might be the next step in efficiency...until it gives birth
| to the next problem.
| ddxxdd wrote:
| >Of course, that flies in the face of all efforts to make
| things green...which involve better insulation, sealing
| windows against leaks, more air filtration systems and etc.
|
| If anyone has a half-hour of time to waste, you can look
| into the science of "countercurrent heat exchangers".
|
| It's fascinating to see how 2 pipes of air current switch
| temperatures when they're in contact and moving in opposite
| directions.
|
| So if you want to be green AND have fresh air constantly
| circulating through a building, then forcing the warm
| inside air to pass by the cold outside air as they
| leave/enter the building can lead to somewhere around 95%
| energy recovery.
|
| Add in a humidifier to the incoming air, and you'll have a
| comfortable room with humidity that will attach to airborne
| droplets, prevent evaporative release of a raw airborne
| virus, and help pull the droplet down to the ground via
| gravity.
| londons_explore wrote:
| Wikipedia claims "Heat recovery systems typically recover
| about 60-95% of the heat in exhaust air".
|
| But even recovering 95% of heat isn't exactly great. If
| you live in Canada and have a 2600 sq ft house with 8 ft
| ceilings and 10 changes of air per hour, and the indoors
| is 70F and outdoors is 0F, thats 2600 _8_ 10 cubic feet
| of air/ per hour, or 12000 BTU/hr. That means you are
| more than doubling your heating costs compared to sealing
| the building and just having conductive losses through
| the walls.
|
| This is true for most climates - even the best energy
| recovery systems still double heating/cooling costs
| compared to having barely any fresh air.
| ddxxdd wrote:
| 10 air changes per hour is a lot; I believe the current
| recommendations for average climates is 3.
|
| And we're looking at the margins; 1 air change per hour
| can do wonders for preventing the spread of disease and
| improving air quality, compared to 0 air changes per
| hour.
|
| Nevertheless, I redid your math, and found that your
| hypothetical home has 26,728 more BTUs of energy in its
| air, compared to the outside air[-1][0][1], and that the
| recommended furnace for such a climate should be 160,000
| BTU/hr [2].
|
| Using those numbers as a base, I find that, with an
| efficiency of 95%, it would require 120 (that's one
| hundred and twenty) air changes per hour to double
| heating costs.
|
| With 60% efficiency, it would require 15 air changes per
| hour to double heating costs.
|
| And it only takes a few air changes per hour to increase
| comfort and prevent illness.
|
| [-1] I suddenly realized that the google search links
| that I used for these calculations are messy and
| unwieldy, so I'll summarize my calculations: (2600 ft^2)
| * (8 ft) represent the volume of the house; (1.225 kg /
| m^3) represents the density of air, (1.005 kJ/(kg *
| Kelvin)) represents the specific heat of air, (70 *
| (5/9)) represents the temperature difference you gave me,
| in Kelvin. Multiplying everything together, and letting
| Google automatically take care of unit conversions, gives
| me 28.2 MegaJoules of energy in the house.
|
| [0] https://www.google.com/search?q=%282600+ft%5E2%29*%28
| 8+ft%29...
|
| [1] https://www.google.com/search?q=convert+28199142.9+jo
| ules+to...
|
| [2] https://www.pickhvac.com/calculator/heating-btu/
| londons_explore wrote:
| My first calculation using entirely imperial units didn't
| go well... I think I'll stick to metric!
| ddxxdd wrote:
| It's unavoidable when discussing residential heating.
| Just use google for automatic unit conversions, and be
| grateful that we didn't need to invoke the cumbersome
| unit of "R-value" to measure insulation!
| graeme wrote:
| Something must be off with your math. I've tested opening
| a window a crack in my building in montreal. The co2 gets
| low even with two people present. Heating costs did not
| double.
|
| Or maybe I had less than ten air changes?
| richardw wrote:
| It can't be that hard to focus on the rooms with people
| in them, reduce the other rooms to eg one change an hour.
| Enginerrrd wrote:
| This is already done when calculating ventilation rates.
| It won't matter much because the majority of space in an
| occupied building is going to be classified as, well,
| occupied.
| Scoundreller wrote:
| I always wonder how much I save by blocking off the vents
| in under-occupied rooms. They end up sitting a few
| degrees cooler in winter.
| rightbyte wrote:
| > It's fascinating to see how 2 pipes of air current
| switch temperatures when they're in contact and moving in
| opposite directions.
|
| Shouldn't the air ideally move in the same direction?
| ddxxdd wrote:
| Nope, because they will both end up at the same
| temperature, namely, the average temperature halfway
| between the two previous temperatures.
|
| In a countercurrent heat exchanger, the hot air will get
| colder and colder until it is at the same temperature as
| the cold air, and the cold air will get hotter and hotter
| until it is the same temperature as the hot air.
|
| This is because the hot air is not warming up the same
| air molecules that it relies on to cool down, and the
| cold air is not cooling down the same air molecules that
| it relies on to warm up. Each current of air gives up a
| part of their heat/coldness, becomes colder/hotter, and
| then moves towards a section of pipe that's even
| colder/hotter than the previous section of pipe.
|
| A picture is worth a thousand words, although it takes
| some staring and studying before the concept finally
| clicks: https://en.wikipedia.org/wiki/Countercurrent_exch
| ange#/media...
| rightbyte wrote:
| Ah ye thank you makes sense.
| [deleted]
| mrow84 wrote:
| There is a diagram illustrating why not in the wikipedia
| article:
| https://en.wikipedia.org/wiki/Countercurrent_exchange
| infogulch wrote:
| > "countercurrent heat exchangers"
|
| Very interesting! The concept makes a lot of sense, and I
| was able to find some companies online that produce such
| a thing, often under the phrase "counterflow heat
| exchanger".
|
| Frustratingly there's little details online for actual
| pricing, but you can find the bare exchange units on ebay
| for $200-300.
| legulere wrote:
| With a controlled ventilation system you have better indoor
| air than with leaky old houses and it's also more energy
| efficient.
| loopz wrote:
| The highest infection rates are still short range though.
| This, combined with being a new virus would still be similar
| to today.
| londons_explore wrote:
| Short range could be explained by airflow rates in most
| buildings being near nil. Someone talks in one spot, and
| pathogens hang around that spot in the air for many
| minutes.
|
| With say 10 air changes per hour (injecting at the ceiling
| and extraction at the floor), and a 3m high building, you
| can expect airflow downwards at about 1 cm per second. That
| means there is perhaps only a 30 second window for a
| particular pathogen to hit someone else's nose before being
| pulled to below face level.
|
| It's not nil, but I think that would lower transmission
| rates by a sufficient factor for COVID (and many other
| diseases) to become extinct.
| a9h74j wrote:
| People talk all the time about air changes per hour. Even a
| recent Nature.com article only discussed this metric.
| However, if you look at suppliers of heat recovery
| ventilation units, a different metric is liters/sec/person.
| About 10 liter/sec/person seems to be pretty good for
| commercial spaces. For home environments people can adapt to
| smells a little better, so the requirements can be lower.
|
| Also: heat recovery percentages don't always include the
| energy required for forced air movement through the
| exchanger.
| clairity wrote:
| yes, and while it might have helped at the margin, it's frankly
| naive to think that we'd have largely avoided this pandemic had
| we just had better indoor air circulation. it's an analytical
| solution (so irresistable to engineers, mathematicians, and
| physicists!) to a complicated and stochastic set of behavioral
| patterns, that people want to be close to each other indoors
| for highly complex and very substantive social reasons (not to
| mention the intricate contraints the virus faces to transmit).
| transmission happens closely face-to-face indoors, and in light
| of that, folks aren't going to want to sit together for very
| long in an airstream strong enough and comprehensive enough to
| deflect and capture potential virus particles everywhere just
| to chat and enjoy each other's company for a bit.
|
| while most mask usage in practice has been completely useless
| (like double-masking or wearing them outside), the one place
| where masks make real sense is between two faces close to each
| other emitting exhaust indoors. if we had just relentlessly
| kept to this one crucial scenario in our mask messaging (and
| simply distancing everywhere else inside), we'd have had much
| better and more targeted mitigation, with dramatically fewer
| downsides to our social and economic lives. and to boot, that
| avoids trying to make extraordinarily costly upgrades to every
| hvac system in the world for marginal benefit.
| [deleted]
| colechristensen wrote:
| It seems overly complicated.
|
| Just raise the air exchange per person and or per volume by a
| significant factor and mandate a very fine particulate filter.
| You could do many measurements and lots of theory but nobody is
| going to engineer their buildings like cleanrooms anyway so the
| results of a lot of science wouldn't be so good regardless.
| f6v wrote:
| Now, who's gonna pay for that?
| bsenftner wrote:
| I bet it's the minimum wage workers, not receiving any bump
| above minimum wage, as well as the lower tier of non-minimum
| wage workers being reclassified to be minimum wage. You know
| those least able to afford it will pay for it.
| disabled wrote:
| > Just raise the air exchange per person and or per volume by a
| significant factor and mandate a very fine particulate filter.
|
| An alternative in the meantime is to use a PAPR (powered air
| purifying respirator), which are more efficient, last much
| longer (device and filter), and are much more comfortable than
| N95 masks. I use an Optrel Swiss Air and cover the valves of
| the mask with a hoodie style balaclava.
|
| It would be a good time to get one, as it is believed that it
| is only a matter of time before SARS-CoV-2 mutates into a
| variant that is capable of evading the vaccines.
|
| Also, the US CDC advice may not have been such a good idea.
| Look at these calculations:
|
| https://twitter.com/DrEricDing/status/1393090966928637952?s=...
|
| Singapore has a comparable vaccination rate to the US and is
| going into lockdown to prevent further spread. They used Pfizer
| and Moderna vaccines. Just some food for thought:
|
| https://twitter.com/andrewkimmel/status/1393086704349630464?...
| nradov wrote:
| It's sad to see people fall victim to mysophobia
| (germaphobia) and related obsessive mental disorders. They
| can be more harmful to overall health than actual viruses.
|
| https://www.webmd.com/mental-health/features/cleanliness-
| rul...
| orhmeh09 wrote:
| You are using concern trolling tactics to accuse someone
| else of mental disorder for taking an interest in safety
| precautions during an uncontrolled global pandemic. This is
| not only rude, it is also dangerous. Please stop.
| dalyons wrote:
| . Singapore is at 31% one shot(from your link), US is at 47
| and rising. Of course you would still be able to get spikes
| in cases at only 31%, that's expected.
|
| The mRNA vaccines are stupendously effective at stopping all
| variants thus far. Not sure what evidence aside from fear
| point to covid being able to mutate past them.
|
| We good, and it's ok to accept that and have hope, not
| everything has to be fear-for-the-worst
| orhmeh09 wrote:
| Is 45-47% efficacy at preventing infection against B.1.351
| & P.1 "stupendously effective at stopping all variants?"
| http://www.healthdata.org/covid/covid-19-vaccine-efficacy-
| su...
| dalyons wrote:
| I may be reading it wrong, but from your link it says 76%
| and 79% (pzifer & moderna) disease prevention against
| 351&p1. Which is still great. Note that's just infection,
| the data shows the vaxxes have near 100% chance of
| preventing you from having more than mild/moderate
| symptoms. So yeah, stupendously effective, and we
| shouldn't be panicking about variants.
| makomk wrote:
| Wasn't Singapore supposed to be one of the few success
| stories for eliminating Covid-19 without using vaccination,
| one of the countries that supposedly proved Western countries
| like the US could've avoided the need for economy-destroying
| lockdowns if only their governments were competent? Not to
| mention that they were and still are one of the most
| aggressive about mandating mask wearing, and were pointed to
| as a demonstration of how effective that was as well. The
| idea that Singapore going into lockdown proves the US CDC was
| wrong to advise vaccinated people don't need to wear masks
| seems extremely dubious.
| esyir wrote:
| We're locking down because of a single cluster. Slightly more
| lenient than the first, but our government is probably just
| being a bit paranoid here. With the vaccines round the corner
| though, that's not necessarily a bad thing.
| londons_explore wrote:
| I'd like to see "air quality inspection" be part of a fire
| safety inspection.
|
| Just have the inspector crack out a CO2 and PM2.5 meter during
| the inspection. Set legal limits and have a fee for exceeding
| them. Make it apply to existing buildings too, so building
| owners can choose to trade off increased HVAC costs Vs reducing
| the fee Vs costs of retrofitting better ventilation.
|
| Obviously the measured numbers vary a lot day to day, so if a
| building owner isn't happy with values measured on the day, let
| them take an average over a week or something.
| cam_l wrote:
| Agree and love the idea about testing.. there are no other
| inspectors (in oz at least) as incorruptible as fire safety
| inspectors.
|
| I had the experience a couple of years ago of working in an
| office with visible smoke from a meat smoker working
| downstairs. The owner and employer had 'independent' tests
| done with no issue found. Fuckers.
|
| I do reckon there is a rather disgustingly unequal
| relationship between people that own or build a building and
| people that have to deal with sickness from working in a
| building.
|
| Overwhelmingly, upfront costs for systems which prioritise
| airchange, occupant health, and energy savings are more
| expensive to install but cheaper in the long run.
| shalmanese wrote:
| That has significant costs on the energy efficiency of
| buildings and would blunt a lot of the progress we're making on
| combating climate change.
|
| Not saying it shouldn't be done but it should be done in a
| smart way that balances between tradeoffs.
| lostmsu wrote:
| Does it? I thought energy expenditure to maintain indoor
| temperature is mostly due to heating/cooling, not due to
| moving air to or from heat exchanger. E.g. it is cheap to
| rotate the air in the building in a closed loop through a
| filter.
| thrdbndndn wrote:
| Yeah, I can't see how the operating cost would be much
| different.
|
| I do think the initial cost to install/upgrade to such
| system would be substantial, though (as in, existing
| systems may not have the capacity to ventilate that much.)
| Robin_Message wrote:
| You can use heat exchangers between outlet and inlet air to
| mitigate a good portion of the energy cost I believe.
| op00to wrote:
| If you have air exchange per person, but some people are in an
| airflow "dead zone", then that doesn't really do you any good.
| You need to ensure the personal area is actively ventilated,
| versus the entire space as a whole.
| stevenhuang wrote:
| Doing that without the ability to quantify the affect is also a
| nonstarter. How would you know it's even making an appreciable
| difference, or if a lower factor would perform just as well?
|
| Without the groundwork theory to rely on, you'd be hard pressed
| to convince new buildings to do something like that on a whim.
|
| > You could do many measurements and lots of theory but nobody
| is going to engineer their buildings like cleanrooms anyway so
| the results of a lot of science wouldn't be so good regardless.
|
| This is a very strange and confused sentiment.
| fiachamp wrote:
| dont need all this complexity to prevent airborne illness from
| going exponential, just masks + contact tracing. the results have
| spoken for themselves in asia
| sebmellen wrote:
| So the idea is to make every room a negative pressure room of
| sorts? I think this is probably long overdue, but I'm afraid I
| don't really see the paradigm shift.
|
| Haven't all of these steps been taken on airplanes already, to
| some extent? From what I see, the "personalized ventilation" idea
| is substantially similar to what aircraft ventilation does, just
| adapted for a workspace/building setting.
| skohan wrote:
| What would be the cost implications of this? I assume we're
| talking about a massive energy requirement/climate impact to
| implement this for all public indoor spaces.
| mjevans wrote:
| It's more important to think about FLOW and also the quality of
| air exiting an air-handling system. BTW, how often are those
| ducts cleaned, if ever?
|
| I would personally love a well designed slightly positive
| pressure dwelling with particle scrubbed inflow and egress
| (some kind of circulated water system like industrial sites
| have). Get rid of that pollen and everything else please.
| sebmellen wrote:
| There's an interesting system called "Phenomenal Aire" that I
| recently installed. It sort of achieves what you're talking
| about, but uses a very different mechanism called "Cold
| Plasma Generation" (caused by dielectric barrier discharge).
| The air smells noticeably "fresher" though that might just be
| due to the ozone. It does seem to have a dramatic
| neutralizing effect on VOCs [0].
|
| Interesting article re: use in meat packing plants [1].
|
| [0]: https://www.sciencedirect.com/science/article/abs/pii/S0
| 3088...
|
| [1]: https://pubmed.ncbi.nlm.nih.gov/33876887/
| sgerenser wrote:
| Isn't ozone supposed to be very detrimental to indoor air
| quality though?
| TheAdamAndChe wrote:
| It is. It's a strong oxidizer and damages your lungs. It
| makes the house smell better because it oxidizes volatile
| organic compounds in the air, but it's horrible for you.
| goldenkey wrote:
| It's an extremely strong oxidizer. It will poke holes in
| your lungs. But sure, it'll also oxidize the other crap
| in your air.
| edward wrote:
| Also here: https://science.sciencemag.org/content/372/6543/689
| chiefalchemist wrote:
| Overall air quality is an issue. We "consume" more air than
| anything else. Every day. All day. Day after day. Pathogens are a
| concern. But conditions and elements that have negative impact on
| the lungs - and help prime such tissue for invaders and disease -
| should be addressed as well.
| x3iv130f wrote:
| I find it regrettable that the things we eat and drink get so
| much more attention than the air we breathe in regards to
| health.
| chiefalchemist wrote:
| It's funny (not) cause bad air is a known killer. Yet it gets
| crickets. I'd add noise to that list as well. Something we
| should be more aware of.
| Huiokko wrote:
| I thought about something like this for the last 10 years when
| taking public transport.
|
| It came again into my mind when I heard about tesla's biohazard
| filter system.
|
| It's just ridiculous how we accept the status quo.
|
| It can't be okay to be sick every year for 5-12 days and covid
| showed me no I don't have to be sick every year and don't get me
| wrong, clearly I'm not getting better in fighting this shit of if
| I have it every fucki g year.
|
| What are long-term effects of being sick every year?
| mhb wrote:
| Sounds swell. Have we started rebuilding our stockpile of N95
| masks yet?
| auxym wrote:
| From industrial suppliers, they are available but about 20X
| more expensive than pre pandemic. We used to buy boxes of 160
| count 3M 8210 for 20$ CAD.
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