my favorite chinese food shop shut down

by the Department of Health & Mental Hygiene! EEKS!!
I went by there(midtown West) yesterday to pick up a couple ‘baozi’ - you know, bun-like chinese snacks - and the door was locked with the bright yellow notice posted in plain view.
It must have just happened - the workers were still standing there, but with no food in sight. It looked like they were in the process of closing shop.
But what? I was still in shock, bewildered that I had frequented a spot that was found to be completely filthy. Who knows what I was eating! Blechhh!!!
Well, their snacks were good, and at 40 cents a pop, the cheapest around. Almost as cheap as in China, and really, only Chinese people (besides me, but then again, I speak Chinese) got food there. But I never ate from their lunch buffet, and I suspect that that was likely where the hygiene problem was found. Or maybe it was the rats in the back. Who knows.
I’m still wondering, though, where does the “Mental” part of the hygiene come from?