Recently there has been an advent of special forces operators, in various areas of operation, that have started wearing thick, heavy beards in the performance of their duties.
There are many reasons this has been allowed, most of them cultural and logistic, as these operators often find it necessary to covertly gather information and to blend into the environment; something that’s hard to do in Afghanistan while sporting a Marine Corps high and tight.
Luckily, the specops guys are not often involved with operations that could be conducive to the use of chemical munitions or gas. Because if they were, they would soon be lying on the ground, gasping and wheezing, regardless of the type and style of mask they were wearing.
That’s because a gasmask only works by being fully sealed. It is for this reason that most police departments and prisons across the US won’t allow their employees to wear beards as facial hair. You should definitly keep this in mind as your preparing for your own family’s defense.