Traditionally, clean shaven its the way to go for an interview, even if you fully intend to grow it back the next week (providing it is allowed on the job).
We do not allow anything but mustaches where I work. I'm sure the respirator part popped up at some point but realistically the company does it because that's how they want their employees to look. Minimal visible tattoos, same ridiculous uniform, collar brass, no hair in the collar, I could go on.
My boss has made it known that she prefers to hire clean shaven people at the interview. If you show up with a beard, that means you like beards and are a risk to violate the uniform standard (slightly flawed but I are where she is coming from).
As an outsider it is not likely you will know a company's uniform policy or how strictly it is enforced. Why violate it accidentally and possibly create a negative when you can just be safe?