Published on July 5, 2025 2:40 PM GMT
Back when I was still masking on the subway for covid (toavoid missing things) I also did some airquality measuring. I found that the subway and stations had theworst air quality of my whole day by far, over 1k ug/m3, andconcluded:
Based on these readings, it would be safe from a covid perspective toremove my mask in the subway station, but given the high level ofparticulate pollution I might as well leave it on.
When I stopped masking in general, though, I also stopped masking onthe subway.
A few weeks ago I was hanging out with someone who works in airquality, and they said subways had the worst air quality they'dmeasured anywhere outside of a coal mine. Apparently the brakingsystem releases lots of tiny iron particles, which are bad for yourlungs like any tiny particles. This reminded me that I'd looked atthis earlier, and since I spend ~3hr in the system weekly (platform +train) it seemed worth going back to masking. I've now been maskingfor a week, and am planning to keep it up.
This is an ElastoMaskPro reusableN95 I got for elastomericfitting. Very easy to breath through, which helps make up for howmy beard makes ithard to get a tight seal.
At $30 (vs $0.60for my favoritedisposable) a reusable one comes out ahead after five weeks if Ifollow the guidance of using single-use ones only once. Now, when Iused disposables I would reuse them many times, but the efficacylikely dropped off a bunch: the fit is worse because the elasticstretches, and they get beat up a bit in my backpack. Likely stillcheaper to use the reusable one, given how long it should last, butwith how I'd use them most of the gains are in efficacy and not cost.
On the other hand, if I wanted to be able to talk to people I'd gowith the disposable: the ElastoMaskPro is worse for intelligibilitythan allthe respirators I tested a few months ago.
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