Explain this to me: Hepa filters protect against TB?

Okay, so even while I wrote a facetious poem a while back titled, "I wish I was stupid," I actually hate stupidity, which is actually what makes my poem more relevant. I hate it when people make rules based on feelings as opposed to science.

It's true I've already written adnauseum about the logic of doing bronchodilator breathing treatments for every bronchospasm and every other lung disease in the book (bronchodilator reform), or giving Tylenol for reasons other than what it's intended for (17 non-indications for Tylenol) , or suctioning patients that don't need it and are awake and alert (as I wrote here).

Today I'm trying to figure the logic of infection control. Today our doctor thinks a patient on a mechanical ventilator "might" have TB, and wants the patient to be in isolation. So the infection control lady walks into the patient's room and says to me, "Why aren't you wearing a hepa mask."

I said, "The patient is on a ventilator and breathing through a closed circuit, and on the exhalation port is a hepa filter. So there is no way any TB particles are in the air in here."

"Well, I want you to wear one anyway."

"Well, that's ridiculous." I protested.

"Well, that's the way it is."

So I did as told.

That's the wisdom of not thinking is that there is no wisdom at all. So someone explain this logic to me, or tell me I'm the idiot. If a patient is on a ventilator, with a hepa filter, isn't that scientifically proven to protect the air from germs from the patient.

If that's not the truth, then why do we bother putting a hepa filter on the vent in the first place?

Of course we have this senseless duplicate hepa filtering when back during flu season we had every patient with the flu getting breathing treatments and thus spreading all those germs all through the hospital. Yes, the flu is spread by airborne contamination.

It's also neat to note there is no filter system in the rooms, and the door is open 24-7. So you don't think, if the hepa filter on the vent isn't doing its job as well as the hepa mask as our infection control person says, that TB particles can't escape out that door.

If this is not senseless stupidity, tell me what it is or is not. I've been wrong before and not afraid to admit it. So do clue me in if you are all the wiser.