Why can't we grow beards?

Specialist. How are you going to properly don and seal your protective mask wearing a beard? Not to mention, grooming, uniformity, cleaning and overall appearance.

During my active duty career, I spent several years designing and working on the M40-series protective mask at Aberdeen Proving Ground. One of the tests we performed put a Soldier into a chamber filled with a corn oil aerosol, and we measured how much aerosol leaked into the mask as the Soldier performed a series of exercises. Our tests showed that the leakage caused by a SINGLE HUMAN HAIR under the mask periphery was enough to result in meiosis (pinpointing of the pupils) in a typical field concentration of nerve agent, and prolonged exposure to that same leakage would result in incapacitation and death. A full beard would be deadly under those same circumstances.

Admittedly, under the current threat environment, nerve agent exposure is unlikely, but would you really want to risk it when circumstances can change so quickly in the modern world, just so you could be furry and impress some girl?

Beard will probably be allowed - in about 20 years. Hang in there.

Cannot seal a gas mask with facial hair

Well rules are rules!

Protective mask seal?

Sp4 Byron Skinner. Back in ancient times when all knuckle draggers could have facial hair overseas in a combat theater it was up to you unit commander and in fact I had facial hair during my combat your and the months I spent in Letterman Medical Center, hey what were you going to do sent me to Vietnam? I don't think giving a court marshal to a Vietnam amputee for some chin whiskers was exactly the kind of publicity the Medical Holding Company who was full of very religious people, prying they wouldn't get orders for deployment to "Nam". Solution terminal leave for three months. The mailman presented me with my Army Retirement certificate and medals.

We were told that we could grow a Mustache / Beard as long as our ID card picture showed us with one. Actually, aboard ship, it was no problem, but it had better be gone when you hit port before you went ashore. This was CG. I don't know what the Navy Regs were.

My understanding when I was in the Army was that it could be dangerous in hand-to-hand combat. The same reason long hair is not permitted.

There are many reasons but at the top of my list would be "try to seal your mask with a beard".