Well… a lot has happened in the past month. Let’s go over them.

Another chemical incident!

Right on cue, the Conyer’s Chemical Plant caught fire. A lot of people have been sharing this guide from 3M on choosing a chemical cartridge. As a reminder from this post, the color coding is pretty useless. Notice for example, that a lot of combinations use ANSI’s “olive” color for any number of chemical cartridge combinations.

Really, the only thing you should pay attention to are the NIOSH abbreviations on the chemical cartridge label, listed here.

Fitting negative-pressure respirators with a beard?

Normally, fit tests and OSHA would insist on beard-users using loud, powered-air-purifying respirators to stay safe, and not catastrophically compromise their fit factor. However, @ghhughes@zeroes.ca noticed that the NIOSH NPPTL was looking into the fit every day, negative-pressure respirators, with beards, with the help of a latex band. The paper that first brought this idea up was published 2021 in Nature, linked here.

And finally…

This paper, which claims to be an N95 RCT. Though astute readers might notice that, unlike other RCTs which simply (and ineffectively!) replace surgical masks with respirators, this RCT insists on qualitative fit tests, exclusion of people with beards, and splitting of respirator users into a group where the respirator is worn only part of the time, and a group where it is worn all of the time.

The group that wore the respirator all the time had the least amount of infections, which should come as no surprise to anyone aware of 29 CFR 1910.134. Despite rigorously following the OSHA protocol, (beards, fit tests, respirator program and all) the paper did not cite it. Again, emphasizing the adage that a respirator only works when you wear it.

And yes, based on this paper, qualitative fit testing is a totally viable type of fit test. No need to insist on a PortaCount fit test to stay safe.