# I made an N95-level mask at home, and you can too

I made a rubber mask brace! I encourage you to make one too; read on for details.

It turns out that surgical masks are made of the exact same material as N95s! They both filter 95% of 0.1μm particles. The only reason N95s are “better” is because they create a tight seal around your face, whereas air leaks out of the sides and top of a surgical mask.

So if you could create a tight seal with a rubber brace (or some rubber bands), then theoretically a surgical mask could be equally as effective as an N95.

## Unsolved Questions

Question #1: How can we share this information more widely? The original Fix The Mask template is copyrighted and I’d like to not get sued, and “don’t wear a cloth mask” sounds suspiciously like fake news. It’s sad that I have to worry about getting sued while trying to help people out, but 🙃.

Question #2: Does a surgical mask shortage still exist? I see that prices are low and masks are widely available for purchase, so the free market price signal tells me there is ample supply. However, I’m unsure if some of this is due to government subsidies, or previously untapped stockpiles. Let me know if you have more information in this area that you can direct me towards.

Question #3: Does buying surgical masks create a shortage for healthcare workers? It doesn’t appear that it does because, again, the free market price signal says otherwise. Additionally, it seems that surgical masks are way easier to produce than N95s because they are simple pressed sheets that don’t require shaping like N95s do.

I’ve seen articles (NPR, PBS) saying that there is a shortage in melt-blown fabric, the raw material of both surgical and N95 masks, however it’s unclear whether the key manufacturing bottleneck is actually the raw material, or rather the fact that shaping the material (or producing “shapeable” melt-blown fabric) adds significant time/complexity/cost that surgical masks don’t accrue, despite being made of the same material.

If the raw material itself is the bottleneck, then how is it possible that there’s huge pallets of surgical masks that I can buy with no limit at Costco for \$0.18 each? Is it that surgical masks appear in good supply because we are repurposing an untapped stockpile that otherwise wouldn’t be used in a healthcare setting? Is the price being subsidized by the government? This is a mystery to me.

If you are (or know someone who is) familiar with the manufacturing process and understand more details about the supply chain and its bottlenecks, let me know where I can look for more information on this.

I only publish half of my writing publicly. The rest are posted exclusively on my private email list: billmei.net/follow (Subscribing is free, no spam ever, and you can safely unsubscribe anytime)

## References

MacIntyre CR, Seale H, Dung TC, et al. A cluster randomised trial of cloth masks compared with medical masks in healthcare workers. BMJ Open 2015;5:e006577. doi: 10.1136/bmjopen-2014-006577

Samy Rengasamy, Ronald Shaffer, Brandon Williams & Sarah Smit (2017) A comparison of facemask and respirator filtration test methods, Journal of Occupational and Environmental Hygiene, 14:2, 92-103, doi: 10.1080/15459624.2016.1225157

Shakya, K., Noyes, A., Kallin, R. et al. Evaluating the efficacy of cloth facemasks in reducing particulate matter exposure. J Expo Sci Environ Epidemiol 27, 352–357 (2017). doi: 10.1038/jes.2016.42

Skaria, S. D., & Smaldone, G. C. (2014). Respiratory source control using surgical masks with nanofiber media. The Annals of occupational hygiene, 58(6), 771–781. doi: 10.1093/annhyg/meu023

Zeng W, Wang X, Li J, et al. Association of Daily Wear of Eyeglasses With Susceptibility to Coronavirus Disease 2019 Infection. JAMA Ophthalmol. 2020;138(11):1196–1199. doi: 10.1001/jamaophthalmol.2020.3906

## Footnotes

1. Their DIY plans used to be free to download, but they removed all references to this and are now trying to monetize via Kickstarter. I have no problem with them trying to make money via the upgraded product they’re selling, but it’s a bad move to remove an open-sourced plan for people who need PPE today and can’t wait 2 months for their Kickstarter product.

They also used to have extensive data on their website that they removed; you can still look up some of their medium.com posts but the information necessary to make your own mask brace has been memory holed.

They used to claim that for “for every 1 N95 produced, you could make 300 surgical masks” in an archived FAQ page, which they removed for some reason. I couldn’t find where they got the 300:1 ratio from, it appears to be based on this NPR article that says “Currently, of the 200 million masks China makes a day, only 600,000 are N95 standard masks”, but that doesn’t mean future production of surgical masks is 300x easier, only that the current stockpile sits at a 300:1 ratio.

2. You can use the calculator to estimate how risky any activity is, and allocate a weekly risk budget towards it. This lets you record how much risk you’re taking to make sure you’re not accidentally taking more risk than you are comfortable with.

Unfortunately the prevalence data are updated weekly instead of daily, but you can fix this by manually editing the location information to plug in the latest testing data from your province/state. If the daily case count happens to be lower than the weekly case count, I would recommend going with the higher (more pessimistic) number because cases appear to recur in 7-day cycles

3. This is what the anti-mask people mean when they say that “masks don’t work”—like all good conspiracy theories it paints fiction with a veneer of truth to appear honest, but where the anti-mask people are wrong is the conclusion should be to try to improve your mask, not to cast it away.