[HN Gopher] Electric cooker an easy, efficient way to sanitize N...
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Electric cooker an easy, efficient way to sanitize N95 masks, study
finds
Author : johnny313
Score : 129 points
Date : 2020-08-08 16:48 UTC (6 hours ago)
(HTM) web link (news.illinois.edu)
(TXT) w3m dump (news.illinois.edu)
| asperous wrote:
| The main thing is consistency, as ovens/cookers are temperature
| controlled. Other bootleg options are available:
|
| Household clothes driers can get hot enough as well, but not all
| of them do.
|
| Cars on a hot day can also get to the desired 140-150f+ range.
|
| Many dishwasher sanitize cycles as well
|
| https://www.who.int/csr/sars/survival_2003_05_04/en/
|
| https://dailyhomesafety.com/does-dryer-kill-bacteria-and-ger...
|
| https://heatkills.org/how-hot/
|
| https://www.quora.com/What-temperature-ballpark-does-the-hea...
| Wowfunhappy wrote:
| Question is whether the oven / dryer / dishwasher damages the
| mask's filter.
| jefftk wrote:
| How does this compare to just letting the mask sit for several
| days?
| Falloodude wrote:
| Cooking the mask ensures that microorganisms on it will die and
| not pose a risk to the wearer. A mask sitting around for
| several days can still harbor them in some cases.
| jefftk wrote:
| I see that in general, but if we're wearing N95s specifically
| to protect against the coronavirus then several days seems
| like it should be (a) enough and (b) not as hard on the mask?
| NeutronStar wrote:
| Sure for CVOID, but then you'd be exposing yourself to
| other microorganism that would probably not become a
| pandemic but still hurt you a little bit.
| coding123 wrote:
| This is what I do. I just place it in a plastic bag and
| don't use it for about a week. I have enough to let me use
| one each day and quarantine the used mask for a week.
| mypalmike wrote:
| What's the plastic bag for? Seems like a good way to
| promote bacterial and fungal growth.
| RobLach wrote:
| Wouldn't that jeopardize the filtration ability of these masks by
| affecting the fields of the electrets under heat?
| weaksauce wrote:
| absolutely. don't do this please. The filter is able to filter
| out particles smaller than 0.3um by using weak electrostatic
| forces. baking it will make the mask less effective. if you can
| just have a few masks that you rotate through... the best would
| be a 3 day rotation.
|
| there's a good reason the CDC doesn't say to do this.
|
| anyway .3 micron particles are the hardest for a mask to filter
| out because they are small and tend to go in a straight line
| more than the smaller particles. the filtration effectiveness
| of the mask is a u shaped curve with a trough in the region of
| the .3 micron particle sizes.
| ConcernedCoder wrote:
| direct sunlight kills everything eventually
| avivo wrote:
| Don't just look at single studies. This is a meta-review
| resource: https://www.n95decon.org/implementation
|
| It's a collaboration among the many people doing research on
| decontamination that also takes into account the tacit
| implementation knowledge of those who conducted the studies.
| everybodyknows wrote:
| Thanks -- within that review we have this link:
|
| https://www.n95decon.org/files/heat-humidity-technical-repor...
|
| There's a table of mask damage as a function of high
| temperature exposure time. All tests were well below the 100C
| cited by OP.
| foobiekr wrote:
| Related: can anyone explain why there are still no n95 masks
| available? It seems like, a few months in, it's surprising that
| there are none available for non-medical buyers.
|
| Is this perception wrong?
| tarikjn wrote:
| I think price-gouging laws could also have something to do with
| this. Suppliers have increased their prices in what is
| essentially protracted inflation from demand. But in most
| states retailers are not legally allowed to increase price tags
| which was triggered in March when most states entered a state
| of emergency/declared disaster [1]. So the results is that
| retailers have to stop stocking these or they lose money; and
| the increased demand doesn't fully reach suppliers which means
| that in turn, manufacturers have also less incentives to
| increase production.
|
| [1] https://www.natlawreview.com/article/price-gouging-laws-
| and-...
| noelsusman wrote:
| They're not widely available to non-medical buyers because
| they're still not easily attainable for medical buyers. N95s
| aren't the easiest thing to manufacturer, so ramping up
| production to fully satisfy current demand would require a
| significant investment in time and capital. Companies aren't
| going to do that without some certainty that they'll actually
| be able to sell enough of their extra production to cover the
| initial investment. Nobody has provided them that certainty, so
| they haven't made the investment. Instead they're (mostly) just
| maxing out production on whatever equipment they already have.
|
| I work for a hospital and have been heavily involved in our
| COVID-related supply chain efforts. Six months into this we are
| still struggling to find a reliable source of high quality
| N95s. Our standard suppliers are getting us 100-200 per day,
| but we're using 10 times that every day.
| Larrikin wrote:
| There is no unified approach to the virus and states and are
| fighting each other for the little supply there is
| romseb wrote:
| Another way to clean masks is to put them in a bowl of hot water
| (at least 70degC) and add detergent. Let it sit for a few minutes
| and you're good to go.
| snissn wrote:
| this will damage n95 masks
| kevin_thibedeau wrote:
| Many N95s are rated for a month (20 days) of 8 hours use. If
| you're only using them for a few hours a day you can stretch
| their life by quite a bit.
| akiselev wrote:
| That's what I've been doing with a pack of N100s and it works
| fine. The problem is threefold: leaving it in a car out in the
| sun will quickly melt the glue holding the plastic filter to
| the mask, after a few uses it just quickly gets contaminated on
| the inside unless you're obsessive about decontamination before
| taking the mask off each time, and that month rating is because
| the plastic fibers used to make the electrostatic filter dry
| out and crumble, which can also be pretty bad for your lungs.
| bitL wrote:
| Why don't you cycle 3-4 of them, wearing a different one each
| day? Viruses won't survive for longer than 3 days inside, so
| cycling multiple masks would solve the possible contamination
| issue.
| jradd wrote:
| what conditions are present to make this a constant? just
| heat and oxygen? moisture?
| sgc wrote:
| 70F / 21C and 50% RH or something close to that, is how
| standard "indoor" environmental conditions are tested in
| general.
| omgwtfbyobbq wrote:
| In my experience I haven't picked up anything because I
| wasn't the best about decontamination, but I have picked up
| something when I wore a surgical mask instead of an N95 mask.
| iscrewyou wrote:
| I've been using one for a while. I put it on for 30 minutes or
| so for only grocery shopping. Then stick it in a paper bag and
| don't touch it for 7 days. Repeat.
| yingw787 wrote:
| I've heard you can use 151-proof grain alcohol in lieu of rubbing
| alcohol (which has disappeared entirely from store shelves for
| months) in order to sanitize things. Apparently if you mix it
| with vegetable glycerin you can create your own ersatz hand
| sanitizer?
|
| I was thinking you could create your own rubbing alcohol by
| mixing water, sugar, and yeast, distill it over your stove, and
| then combine it with aloe vera to create hand sanitizer, but
| that's probably less preferable than using store-bought
| ingredients that are more consistent.
| buildbot wrote:
| I'm not a medical professional, but since 151 is basically 75%
| ethanol, and ethanol is sold as a cleaner/disinfectant when
| pure, i assume it would work well.
| akiselev wrote:
| Please don't disinfect an N95 or N100 mask with alcohol (of any
| sort). It will dissolve the plastic fibers of the filter.
| wrycoder wrote:
| How do you know this?
| klyrs wrote:
| https://smartairfilters.com/en/blog/sanitizing-masks-with-
| al...
| DanBC wrote:
| If you're going to DIY hand sanitizer you may want to follow
| this WHO guidance:
| https://www.who.int/gpsc/5may/Guide_to_Local_Production.pdf
| petra wrote:
| Generally,the instant pot requires at least 1 cup of water when
| running, according to the manual.
|
| How does this work without water ?
| lightlyused wrote:
| You can put another container inside the instant pot to hold
| the masks. That is how you make things like cheese cake in
| them.
| petra wrote:
| But steam may ruin the masks, and the instructions on
| sanitizing don't mention water.
| masklinn wrote:
| I'm also wondering, IIRC rice cookers rely on the temperature
| of the pot not exceeding 100C until all the water has
| evaporated (which is why getting the correct rice/water amount
| is important). Without any water in the container I would
| expect the pot to quickly exceed 100C and shut off.
|
| Mine certainly seems to provide no way to maintain such a
| temperature, I'd guess it'd just switch to "keep warm" and
| AFAIK that's nowhere near 100C (maybe 60~70).
| weaksauce wrote:
| the cheap rice cookers use a temperature switch that triggers
| after it reaches a bit over 100C yes.
| joshvm wrote:
| There's no reason you can't run these pots without water (in
| theory). I don't think you'd damage the heating elements
| themselves. This is an issue for heating _wire_ like NiChrome
| where if you put a high current through it, it 'll melt. The
| elements in a slow cooker could probably handle a much higher
| current than you would normally use. And obviously the elements
| themselves can withstand the nominal operating current. I'm
| assuming a slow cooker/crock pot, _not a rice cooker_. The one
| I have at home is very very simple, electrically. Rice cookers
| are a bit more complicated and might be more finnicky because
| they have to go through some fairly accurate states within a
| short amount of time (and make assumptions about the level of
| rice /water in the cooker).
|
| It probably depends if your pot has a thermostatic control or
| not. Some pots might damage their coating if there is no "load"
| to sink the heat into. Fancier units might shut off if they
| detect that they're being run empty. Cheaper pots might put out
| enough heat that if nothing is in them, they'll damage the non-
| stick. But if your pot is designed to hit a set temperature, it
| should be OK regardless of whether there's anything in it.
|
| Anecdote - our milk frother (a cheap Lavazza Mi Moda) has fill
| levels for heat/foam, but is also clearly thermostatic. The
| second time you run it (say if you make two cups back to back),
| it takes much less time to indicate it's finished when it
| starts from warm. My guess is that it's designed to heat the
| milk up to a preset temperature (measured using the wall of the
| chamber) and then it ramps up the whisk for a preset period of
| time.
|
| I really doubt cheap slow cookers use PID loops to control the
| temperature. They're normally "bang bang" relay driven - they
| hit a set temperature and the elements turn off. When the temp
| decreases they turn on again. Perhaps if there's no load in the
| cooker they'll keep over/undershooting.
|
| You might be able to put a piece of something like cast iron in
| there to heat up initially, then when the unit is up to 100C,
| take it out and replace with the towel/masks. My guess would be
| you want to avoid an initial thermal runaway more than anything
| else. Also if you're using a crock pot for covid sterilisation,
| maybe you don't want to use it for food!
| syshum wrote:
| Would that not depend on the type of Instant pot you have?
| There are so many now
|
| Many of a Sautee mode used to brown meat, I dont think you need
| a 1 cup of water for that? or the ones with the Air Fry
| attachments...
| Abishek_Muthian wrote:
| I wonder whether the results change with the pressure cooker.
|
| I had ilizarov apparatus[1] on my legs for over a year(once
| during age 7 and another during age 15) and my mom used to
| sterilise the instruments (Scissors, Forceps) used for dressing
| wounds at home(every alternate day) in pressure cooker(on advice
| of the doctor).
|
| I presume, pressure cookers are still being used for the
| sterilisation of instruments[2] in several parts of the world as
| its still common than an electric cooker.
|
| [1]https://en.wikipedia.org/wiki/Ilizarov_apparatus
|
| [2]https://cdn.ymaws.com/sites/adint.site-
| ym.com/resource/resmg...
| everybodyknows wrote:
| Do not do this. Pressure cookers exist to accelerate cooking,
| by raising the boiling point of water above 100C, because
| pressure resists boiling. All plastics in the mask will
| deteriorate rapidly.
| necovek wrote:
| I am sure they perform sterilization effectively, but
| introduction of water/steam (which is under pressure in a
| "pressure" cooker) will almost certainly deform a mask like an
| N95 mask.
| Abishek_Muthian wrote:
| I thought electric cooker uses less water in contrast to no
| water.
| clairity wrote:
| if your concern is corona, there's no need to do any of this for
| most people, most of the time (i.e., not a front-line worker).
| the likelihood of getting live corona on the mask is pretty low,
| and any corona that does get on the mask will die naturally
| overnight. certain situations like going to a party might warrant
| it, but in that case, just throw the mask away and use a new one
| next time.
|
| if you're more worried about other bacteria and viruses, it's a
| little more relevant, but not much for most of us. despite the
| endless news coverage, it's just not worth worrying about unless
| you're often in elevated risk situations, like being a medical
| worker. just wash your hands occasionally (particularly after
| situations like going to the bathroom or handling raw meat).
| gfodor wrote:
| You make a lot of claims here about how to properly protect
| oneself, and as matters as important as this one, citations
| should be considered strictly necessary.
| BoiledCabbage wrote:
| And the reasons people ask for citations is what you are saying
| is very misleading. The CDC estimates that 45% of US Adults
| fall into these increased risk categories. So no, it's not just
| people fighting off cancer it's almost half the country.
|
| > We estimated that 45.4% of US adults are at increased risk
| for complications from coronavirus disease because of
| cardiovascular disease, diabetes, respiratory disease,
| hypertension, or cancer. Rates increased by age, from 19.8% for
| persons 18-29 years of age to 80.7% for persons >80 years of
| age, and varied by state, race/ethnicity, health insurance
| status, and employment.
|
| 1. https://wwwnc.cdc.gov/eid/article/26/8/20-0679_article
| clairity wrote:
| none of that makes any difference. basically no one needs to
| disinfect masks, including those at elevated risk (emergency
| personnel and hospitals facing shortages the likeliest
| exceptions). just wear your mask at appropriate times
| (indoors when you can't distance from strangers for extended
| periods of time). regular folk don't need to do more than
| that.
| tedunangst wrote:
| What did the parent comment say about people fighting cancer?
| andai wrote:
| Am I reading this right, does this mean that _45%_ of the
| country has a serious pre-existing medical condition?
| erichurkman wrote:
| > A greater percent of men (47%) have high blood pressure
| than women (43%)
|
| https://www.cdc.gov/bloodpressure/facts.htm
| pydry wrote:
| I bought one of these UV sanitizer boxes to sanitize my N95s:
| https://www.amazon.co.uk/gp/product/B085XZPLVS/ref=ppx_yo_dt...
|
| I'm still not totally certain how well it really works, but I
| know it works better than those UV wands (you need at least a few
| minutes of exposure).
|
| It's also neat for a few other things that it's probably healthy
| to sterilize a bit more frequently (e.g. keys, phone, toothbrush
| heads).
| hbcondo714 wrote:
| Yup, my wife went all out and got one of those UV sanitizer
| boxes[1] too along with the Under Armour face masks[2]. Their
| instructions say to wash it but it's convenient to just place
| in a box. We have also been cleaning other items in there
| including baby toys.
|
| [1] https://lumolite.com/
|
| [2] https://www.underarmour.com/en-us/p/ua-
| sportsmask/1368010.ht...
| everybodyknows wrote:
| Underarmour.com:
|
| > Polyurethane open-cell foam lets air through ...
|
| And virus particles.
| Johnny555 wrote:
| I can understand how UV light can sterilize hard surfaces
| like a cell phone, but how does it sterilize multi-layer
| fabrics where the virus may be shaded from the UV light by
| the fabric?
| hbcondo714 wrote:
| Their website states and shows that face masks are items
| you can sanitize. They also have a testimonial from a
| health care worker that uses it for masks. Neither go into
| details but their FAQ page says "UV-C light only
| sanitizates surfaces it can reach" so that is a fair
| question you are asking they should address.
| cf100clunk wrote:
| An autoclave is what the electrical cooker is being used to
| emulate. A pressure cooker is a better option if you'll be on the
| road, camping, or otherwise without electricity. Researchers in
| Canada already proved several months ago that N95 masks could be
| sanitized this way:
|
| https://news.ycombinator.com/item?id=22761264
| anotheryou wrote:
| I rotate 10 masks, wear each of them 20m/day at most. Drop out of
| rotation if smelly (only happened once with serious sweating).
| everybodyknows wrote:
| SARS Cov-2 infectiousness decays exponentially, with the time
| constant a function of temperature and humidity. A two-parameter
| calculator:
|
| https://www.dhs.gov/science-and-technology/sars-calculator
| jdc wrote:
| Sounds like wetting the towel first would be the way to go.
| afterburner wrote:
| Cooking a wet towel would turn the water to steam, I'm
| guessing that would be problematic for the mask's durability.
|
| Also, the humidity factor seems counter intuitive to me on
| that site. I thought the virus survived longer in the air in
| damp spaces, while sunlight dried out the virus rendering it
| inert.
| Jerry2 wrote:
| My family has been decontaminating our N95 masks with ozone. I
| bought a battery-operated O3 generator and if you place it into a
| tupperware container along with the mask, it will decontaminate
| it and then you can use it the next day. Yale School of Medicine
| has done a study on the efficacy of this method. [1]
|
| I prefer this method because it doesn't degrade the mask at all,
| it needs no disinfecting/harsh chemicals, it penetrates into the
| pores of the mask completely, and it's near fool-proof.
|
| [1]
| https://www.medrxiv.org/content/10.1101/2020.05.28.20097402v...
| rayuela wrote:
| Wow this is actually incredible if this works. However this
| study was tested bacteria and relate it to covid in the
| following way:
|
| "an ozone application achieves a high level of disinfection
| against PsA, a vegetative bacteria that the CDC identifies as
| more difficult to kill than medium sized viruses such as SARS-
| CoV-2 (Covid-19)"
|
| Would the implication be that this same method works on covid
| as well? That is not immediately apparent to me...
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