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]<p>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.<p>[1] <a href="https://www.medrxiv.org/content/10.1101/2020.05.28.20097402v1" rel="nofollow">https://www.medrxiv.org/content/10.1101/2020.05.28.20097402v...</a>
The main thing is consistency, as ovens/cookers are temperature controlled. Other bootleg options are available:<p>Household clothes driers can get hot enough as well, but not all of them do.<p>Cars on a hot day can also get to the desired 140-150f+ range.<p>Many dishwasher sanitize cycles as well<p><a href="https://www.who.int/csr/sars/survival_2003_05_04/en/" rel="nofollow">https://www.who.int/csr/sars/survival_2003_05_04/en/</a><p><a href="https://dailyhomesafety.com/does-dryer-kill-bacteria-and-germs/" rel="nofollow">https://dailyhomesafety.com/does-dryer-kill-bacteria-and-ger...</a><p><a href="https://heatkills.org/how-hot/" rel="nofollow">https://heatkills.org/how-hot/</a><p><a href="https://www.quora.com/What-temperature-ballpark-does-the-heated-dry-function-of-a-dishwasher-operate-at" rel="nofollow">https://www.quora.com/What-temperature-ballpark-does-the-hea...</a>
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.<p>Is this perception wrong?
SARS Cov-2 infectiousness decays exponentially, with the time constant a function of temperature and humidity. A two-parameter calculator:<p><a href="https://www.dhs.gov/science-and-technology/sars-calculator" rel="nofollow">https://www.dhs.gov/science-and-technology/sars-calculator</a>
Don't just look at single studies. This is a meta-review resource: <a href="https://www.n95decon.org/implementation" rel="nofollow">https://www.n95decon.org/implementation</a><p>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.
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.
I wonder whether the results change with the pressure cooker.<p>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).<p>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.<p>[1]<a href="https://en.wikipedia.org/wiki/Ilizarov_apparatus" rel="nofollow">https://en.wikipedia.org/wiki/Ilizarov_apparatus</a><p>[2]<a href="https://cdn.ymaws.com/sites/adint.site-ym.com/resource/resmgr/NewsArticles/Use_of_pressure_cookers_for_.pdf" rel="nofollow">https://cdn.ymaws.com/sites/adint.site-ym.com/resource/resmg...</a>
I have a set of N99 masks that I just rotate over a period of about a week in brown paper bags.<p>If you don’t have enough masks for that, I imagine a sous vide machine (like the Joule) would work. Just seal the mask in a plastic bag and place under water for the appropriate amount of time. These things hold very precise temperatures.
I bought one of these UV sanitizer boxes to sanitize my N95s: <a href="https://www.amazon.co.uk/gp/product/B085XZPLVS/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&psc=1" rel="nofollow">https://www.amazon.co.uk/gp/product/B085XZPLVS/ref=ppx_yo_dt...</a><p>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).<p>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).
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:<p><a href="https://news.ycombinator.com/item?id=22761264" rel="nofollow">https://news.ycombinator.com/item?id=22761264</a>
I don't want to appear a naysayer, but everyone should be aware that N95 masks usually aren't effective at the intended level because of the lack of a fit test and training by the non-professional users.<p>See:<p><a href="https://news.ycombinator.com/item?id=23957506" rel="nofollow">https://news.ycombinator.com/item?id=23957506</a>
None of this is necessary for non-healthcare workers, since the virus will die off on a fabric mask in a few hours.<p>1) Not a single study has demonstrated that viable Sars-Cov-2 virus survives on porous materials in the real world<p>2) Even before Covid, it was known for decades (common medical knowledge) that human coronaviruses and flu viruses do not remain viable on porous materials for more than several hours.<p>That this common knowledge is not so common knowledge among the public is a failure of public health communication. The one or two alarmist studies showing that the virus "survives" X number of days don't reflect the real world because 1) the researchers literally directly douse or soak the surface with a huge viral load, and 2) the researchers usually only look for viral genetic material, not whether the virus can infect cells. Viability != detecting viral genetic material (same story for people - we shed viral genetic material long after we stop being contagious).<p>There is a reason the CDC has always said surface transmission is rare: <a href="https://www.nytimes.com/2020/05/22/health/cdc-coronavirus-touching-surfaces.html;" rel="nofollow">https://www.nytimes.com/2020/05/22/health/cdc-coronavirus-to...</a> there have been no documented cases of surface transmission: <a href="https://www.cdc.gov/coronavirus/2019-ncov/prevent-getting-sick/cleaning-disinfection.html" rel="nofollow">https://www.cdc.gov/coronavirus/2019-ncov/prevent-getting-si...</a> Fortunately some in the media are catching on to the hygiene (security) theater: <a href="https://www.theatlantic.com/ideas/archive/2020/07/scourge-hygiene-theater/614599/" rel="nofollow">https://www.theatlantic.com/ideas/archive/2020/07/scourge-hy...</a><p>Citations for 1) and 2):<p>Most studies use unrealistic starting doses: <a href="https://www.thelancet.com/pdfs/journals/laninf/PIIS1473-3099(20)30561-2.pdf" rel="nofollow">https://www.thelancet.com/pdfs/journals/laninf/PIIS1473-3099...</a><p>Other human coronaviruses don't survive long on porous surfaces (gone by 6 hours): <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7134510/" rel="nofollow">https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7134510/</a>. A hospital randomly collected patient and real surface swabs (including non-porous surfaces) for original SARS, a minority were PCR positive, none of the swabs were infectious (viral culture): <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7134510/" rel="nofollow">https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7134510/</a>. Same story for flu (virus can be detected for days, but inactive and not viable after a few hours): <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3222642/" rel="nofollow">https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3222642/</a>.<p>I could only find this study on Sars-Cov-2 that cultured the virus (still used a huge viral dose in a lab setting, not the real world). Even though they were able to culture the virus, only 1% of virus remains after 6 hours on a surgical mask, several orders of magnitude less for cotton clothing: <a href="https://www.medrxiv.org/content/10.1101/2020.05.07.20094805v1.full.pdf" rel="nofollow">https://www.medrxiv.org/content/10.1101/2020.05.07.20094805v...</a><p>This long post was originally meant to be a reply to someone asking for a citation; it's yet another example of how much effort is required to combat misinformation.
My big concern is modifying the electrostatic properties of the fibers which is how much larger fibers stop much smaller particles (order of 10x-100x). It looks like moderate heat and no humidity in this study didn't have those effects. Hoping this can be peer reviewed soon!
Can someone explain why you can’t just have three masks, and circulate through them? We’ve been told that the virus dies after 3 days just sitting there. Why do I need to decontaminate it ad in TFA? I don’t get it.
Another way to clean masks is to put them in a bowl of hot water (at least 70°C) and add detergent. Let it sit for a few minutes and you‘re good to go.
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.<p>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).
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?<p>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.