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Researchers create air filter that can kill the coronavirus
- Causality1 6y agoIs there any evidence that the virus can survive passage through a normal air filter/AC system and infect humans?
- javajosh 6y agoThat's a difficult thing to test directly, so I think most people reason it out. In this case, you think about the virus, its interaction with air particles, and the interaction with a typical AC system with and without (unheated) filtration. I think the issue with ordinary filtration is that the virus is very small and can pass through most filters; by heating it the virus only needs to collide with the hot filter once, or (I think) get knocked around by fast air molecules to become unviable (is "killed" the right term for a virus that may not be "alive"?) Long story short, I think this invention looks great and I for one would use one, especially in cold climates where I already want to heat up the air.
- stubish 6y ago> Long story short, I think this invention looks great and I for one would use one, especially in cold climates where I already want to heat up the air. If it also works on influenza, it would be a fantastic way to heat buildings during flu season, and the investment could pay for itself even after the current COVID pandemic.
- ipsum2 6y agohttps://wwwnc.cdc.gov/eid/article/26/7/20-0764_article https://wwwnc.cdc.gov/eid/article/26/7/20-0764_article > During January 26–February 10, 2020, an outbreak of 2019 novel coronavirus disease in an air-conditioned restaurant in Guangzhou, China, involved 3 family clusters. The airflow direction was consistent with droplet transmission. To prevent the spread of the virus in restaurants, we recommend increasing the distance between tables and improving ventilation.
- belltaco 6y agoThe virus didn't come through the ac system in that case. The AC was just blowing air from the infected person to others. This solution would have been useless.
- saeranv 6y agoAnother solution I have thought about is simple increasing the amount of fresh air brought into an indoor space. Laboratories, wood-working shops and other spaces that can produce unhealthy air have extremely high Air Change per Hour (ACH)[1] requirements. It's wasteful[2] since you also have to condition that air, but it seems like a simple solution to ensuring we dilute air swarming with potential virus. [1] https://www.engineeringtoolbox.com/air-change-rate-room-d_867.html https://www.engineeringtoolbox.com/air-change-rate-room-d_86... [2] You can limit it a little bit with demand control ventilation, which monitors C02 exhaled by occupants and tunes ventilation accordingly.
- dehrmann 6y ago> It's wasteful since you also have to condition Heat exchangers can help, but it's still obviously less efficient.
- saeranv 6y agoYes, and another big saver would be certain types of heat recovery system[1] that will allow you to recover the heat added to the supply air from the exhaust air without mixing (and thereby polluting) the air streams. [1] https://en.wikipedia.org/wiki/Heat_recovery_ventilation#:~:text=Heat%20recovery%20is%20a%20method,thus%20energy%20costs%20)%20of%20buildings.&text=Heat%20recovery%20systems%20typically%20recover,the%20energy%20efficiency%20of%20buildings%20 https://en.wikipedia.org/wiki/Heat_recovery_ventilation#:~:t....
- redis_mlc 6y agoFYI: Legionnaires' Disease is spread through HVAC systems that use cooling towers: https://en.wikipedia.org/wiki/Legionnaires'_disease https://en.wikipedia.org/wiki/Legionnaires'_disease
- hedora 6y agoThat’s because the cooling towers incubate the bacteria that causes Legionnaires. COVID is caused by a virus that won’t reproduce outside of mammals.
- bradknowles 6y agoYes. Why do you think hospitals have HEPA filters in the first place?
- joe_the_user 6y agoThe filter heats air to 200 degrees. I assume the air would have to be cooled afterwards. Is that going to use an insane amount of energy or is there some trick to heat and cool without that much energy (a la air conditioning).
- redisman 6y agoAir conditioning exhausts a lot of heat. Maybe it can reuse some of that. I might be missing some weird physics scaling though if you're air conditioning 200F temperature air maybe a normal A/C can't handle that.
- dbcurtis 6y agoNo, the filter is heated to 200C, not the air. They don’t say what the temperature delta of the air is after passing through.
- joe_the_user 6y agoGood point, though if air continually passing through, the temperature delta would be significant.
- praptak 6y agoThe article says the virus is deactivated at 70C, so the air itself should probably get to 70C plus perhaps a safety margin. Come to think of it, if you coupled that with a heat exchanger, the filtered air could pre-heat the incoming air and get cooled in the process. This way the filter would only have to transfer enough heat to make up for the inefficiency of the exchanger. I'm not sure if this is feasible.
- dTal 6y agoIt's probably perfectly feasible - it's the same working principle as a dehumidifier, except temporarily heating instead of temporarily cooling. Just reverse the polarity and you're set!
- adrianmonk 6y ago
- elif 6y agoIs there a fundamental reason why UV doesn't work on air? Wouldn't a UV approach be much more energy efficient and rapidly scalable?
- catherd 6y agoIt does work on air. Some commercial HVAC systems integrate UVC lamps. It needs relatively high power or a long straight run where the air flow and light are both pointed in the same direction. https://en.wikipedia.org/wiki/Ultraviolet_germicidal_irradiation#Air_disinfection https://en.wikipedia.org/wiki/Ultraviolet_germicidal_irradia...
- bradknowles 6y agoYup. You can even buy them for home AC systems. Both of our AC units include UV lamps, and we bought them years ago. And they include whole-home HEPA filters, too. And our room IQAir HyperHEPA filter units go down to 0.003 microns, which is an order of magnitude smaller than virus particles. But that only helps you at home, and it only helps you with those particles it captures before you breathe that air. If you’re between the air filter and the virus particles in question, then you’re more likely to be the filter that catches those particles.
- hedora 6y agoWhy not use a HEPA filter? Surely, if it can filter heavy isotopes, coronavirus won’t fit through. Coronavirus doesn’t last more than a few days without a host, so the HEPA filter will eventually “kill” 100% of the virus as well. Also, ~8-18% of the population (mostly women) is allergic to nickel due to A combination of genetic predisposition prolonged contact with nickel-coated jewelry. Presumably this filter dumps trace amounts of nickel dust into the air. What could go wrong?
- owyn 6y agowow, interesting. I'm male but recently discovered I'm allergic to nickel after 30 years of playing guitar (electric guitar strings are usually nickel composite materials) but I didn't realize it was that common. I kinda self diagnosed it but I'm almost happy it's a common thing.
- dehrmann 6y agoYou should look into stainless steel frets and either non-nickel or coated strings.
- rmellow 6y agoWhat are the symptoms of that allergy?
- chooseaname 6y agoAppears to be the usual[0]: rash, redness, itching, etc. [0] Not minimizing this, it’s just that our bodies tend to react to allergens in certain ways.
- tru3_power 6y agoWhy does prolonged contact with nickel trigger this? I thought this was basically the purpose of allergy shots (expose you to the allergen over a period of time)
- 6y ago
- guidedlight 6y agoThis company claims its air filter kills the virus too. https://cleanairexp.com/ https://cleanairexp.com/
- reaperducer 6y agoThe difference is that the one linked above was tested at the Galveston National Laboratory and works well enough that it also kills 99.9% of anthrax spores.
- glaive123 6y agoDo viruses actually die? I thought they are not living.
- andrewxdiamond 6y agoThey can deteriorate to the point that they can no longer reproduce, so, close enough?
- thdrdt 6y agoYou are right. 'die' refers to falling apart. I am not an expert but I believe the reproduction of a virus is more 'chemical' than 'biological'.
- gpvos 6y agoIt's very much biological. Viruses, like our cells, consist for a large part of protein, which degenerates when above 65 degrees for some time.
- buboard 6y agoneither are processes
- rbanffy 6y agoIf you write an executable to a file, does the program still exist? Or is its existence as a program depend on it being loaded in memory and being executed?
- wang_li 6y agoThey deactivate. But it’s a distinction without value for casual conversation.
- asdff 6y agothey can be lysed and degraded
- aj7 6y agoHow efficiently are the aerosols and droplets sucked into the AC system? The principal method of spread is by these vehicles, person-to-person, at close range. Imagine a church with most pews filled. If the AC provided absolutely pure air (forget for the moment about how this is created), it would do little to prevent virus spread between unprotected individuals.
- kijin 6y agoYou could, in theory, build a system like what they use in datacenters. Drill holes in the floor and ceiling and create enough vertical airflow that any particles you expel will be sucked either up or down before they reach the next person. That would make a very uncomfortable church to sit in, though.
- usrusr 6y agoI'm basically taking this from an earlier hn discussion about the lack of a documented early outbreak in Las Vegas: apparently the casinos have systems powerful enough (and surely involving clever placing of inlets and outlets to enforce a coherent vertical stream) to allow indoor smoking without driving away non-smoking customers. This has since become my mental model of what it would take to make an indoor environment as safe(ish) in the pandemic as the outdoors.
- toast0 6y agoThe indoor air quality at casinos with smoking is better than a bar with smoking, and it's not enough to drive me away from walking through the casino to get to the hotel, but your clothes still smell like smoke when you get to your room. I would put it as tolerable, maybe if I enjoyed gambling or drinking, I'd be ok with being on the casino floor for longer. Better to go to the enlightened casinos with no smoking though.
- Marsymars 6y agoFor my mental model, I usually think of underground mine ventilation. Requirements are typically in the range of several cubic metres per minute per person - enough ventilation to be able to feel a light breeze.
- deleted 6y ago[deleted]
- codecamper 6y agoso for this to work, all the air in a room must be heated to 250C for a short time while it passes through the filter. How much energy does that use?
- mschuster91 6y agoNo, the filter gets heated to 250 °C to destroy trapped viral particles. The air itself won't get heated up much, its contact time with the filter is too short.
- gpvos 6y agoYou'll have to heat up the air, or at least all particles in it, to at least 65 degrees to deactivate the virus.
- mschuster91 6y agoThe viruses get trapped in the filter and burned up there by the 250 °C, so no need to heat up the air to 65°C.
- mootzville 6y agoSo, I can just vent through my oven?
- donogh 6y agoThere are plenty of commercial air purifiers that will at least trap SARS-CoV-2 particles, and they can be added to air conditioning systems. The IQAir HealthPro Plus, which can be bought for $899[1], filters particles as small as 0.003 microns (Coronavirus is approximately 0.1 microns[2]). And their Perfect 16 product is designed for HVAC systems[3]. [1] https://www.sylvane.com/iqair-healthpro-plus-air-purifier.html https://www.sylvane.com/iqair-healthpro-plus-air-purifier.ht... [2] https://abcdust.net/how-large-is-a-corona-virus-virion-compared-to-the-mp10-2-5/ https://abcdust.net/how-large-is-a-corona-virus-virion-compa... [3] https://www.sylvane.com/iqair-perfect-16-air-purifiers.html https://www.sylvane.com/iqair-perfect-16-air-purifiers.html
- Shalle135 6y agoIs there any good reason to research this at all since the virus is mainly transmitted through surfaces and is not in itself airborne? Sure there are drops that can last long enough in the air to infect people but it’s far from the biggest point of infection.
- empath75 6y agoAFAIK you have it exactly backwards.
- cableshaft 6y agoPretty sure you've got it backwards there. Surface transmission is what's supposed to be 'while possible, it's not too likely', and respiratory droplets are supposed to be the main way it spreads (with recently 239 scientists begging WHO to acknowledge it can be spread through the air also, not just the larger droplets, which fall to the ground a lot faster). Here's what CDC says: "The primary and most important mode of transmission for COVID-19 is through close contact from person-to-person. Based on data from lab studies on COVID-19 and what we know about similar respiratory diseases, it may be possible that a person can get COVID-19 by touching a surface or object that has the virus on it and then touching their own mouth, nose, or possibly their eyes, but this isn’t thought to be the main way the virus spreads." https://time.com/5863220/airborne-coronavirus-transmission/ https://time.com/5863220/airborne-coronavirus-transmission/ https://www.cdc.gov/media/releases/2020/s0522-cdc-updates-covid-transmission.html https://www.cdc.gov/media/releases/2020/s0522-cdc-updates-co...
- ggrothendieck 6y agoThis may destroy viruses but it does not kill them as viruses are not alive.
- johnnymonster 6y agoWhat could go wrong with a 400F heating element on in your air ducts at all times. Wouldn’t it constantly be lighting hair and dust particles on fire???
- ColanR 6y agoOne of the primary causes of housefires is leaving bathroom fans running.
- sgerenser 6y ago[citation needed]. A quick google search shows some warnings about this happening (due to lint and dirt building up and the motor overheating) but I’d be very surprised if it’s even in the top 10.
- ColanR 6y agoIt's what the firefighter told my parents when the bathroom ceiling fan burned our house down.
- sizzle 6y agoReally?? I always do this and now I'm worried, got a source? A normal fan or the fans with the heat lamp bulbs integrated?? Cause I can see those starting a fire with the intense heat it generates.
- jiofih 6y agoCan’t every UV-C equipped filter kill the virus? Why would a heat based system be preferred?
- nikolay 6y agoAren't salt crystals killing it to? Many had home-made masks with salt based on studies.