I have brought FFP3 masks half a year ago and at the time I brought them to get outside and protect myself in enviroments with allergy triggers. It didn't work. At the time I wasn't aware that fit testing is hard as writes:

Fit-testing is a laborious task, taking around 30 min to do properly, and comprises qualitative fit-testing (testing whether the respirator-wearing healthcare worker can taste an intensely bitter or sweet substance sprayed into the ambient air around the outside of the mask) or quantitative fit testing (measuring the ratio of particles in the air inside and outside the breathing zone when wearing the respirator). Attempts have been made to circumvent the requirement for fit testing, and it has been suggested that self-testing for a seal by the respirator wearer (see http://youtu.be/pGXiUyAoEd8a for a video demonstration) is a sufficient substitute for fit-testing. However, self-checking for a seal has been demonstrated to be a highly unreliable technique in two separate studies so that full fit-testing remains a necessary preliminary requirement before respirators can be used in the healthcare setting.

There are many people who seem to wear masks in this crisis in a way that's doesn't provide as much protection as the mask could theoretically give them.

Having protocol that individuals can use for self-checking that's reliable would be very valuable.

In particular it would be good to know what solutions to use for the smell test. Do you have to take take to use moleculs that have the right size?

New Answer
Ask Related Question
New Comment

1 Answers sorted by

Other comments on the post (https://slatestarcodex.com/2020/03/23/face-masks-much-more-than-you-wanted-to-know/) indicate that fit testing is much easier to accomplish with an elastomeric respirator (often referred to as "P100" due to the filter).

>"Only a handful of people in my training platoon of 50 completely lost their shit"


>Gas mask training was my favorite day because everybody got to feel their mucus membranes start to vent everything while a sergeant screamed at them that they were screwing up things that a baby could do right.



Unfortunately, even if it is not hard to get a good fit, fit testing may be cost-prohibitive. After checking the prices for 3M, MSA, and Allegro, I found that the median price of a fit test kit is $363.50 (25th percentile is $296.25 and 75th percentile is $463.36).

After you buy all the pieces (2 respirators with plans to return the one that doesn't fit, 2 sets of cartridges, fit test kit) from Amazon.com and Fisher Scientific, the cost is >=$290 as of January 8, 2022 excluding shipping and taxes.

New to LessWrong?