HJL,
There was a comment in the article by R.W., “What We Lack in Training Can Be An Advantage“. It is tough to put pen to paper and generate something of value, and I would like to complement their efforts; for the most part I have no issues. However, sometimes what may seem reasonable and practical can in fact be more dangerous. Regarding the use of gas masks for respiratory protection, it stirred some memories from back in the days when I went to NBC School in the Army, from 30+ years ago.
One of the things I remember was regarding use of Gas Masks in a Nuclear environment. Because the radioactive particles will be captured and stored in the filters, this will result in your face being cooked by the radiation the longer you wear the mask. If I recall correctly, the instructors recommended bandanas/cravats around your mouth/nose to protect yourself.
If you plan to use any mask for respiratory protection in a radioactive environment, remember to dispose and replace the filters as soon as you are out of harms way. – Steve T.