Man-of-the-Atom

So my brother has spent the last hour or so doing mad science on his whiteboard and I didn’t question I thought it must be school work or something. As it turns out he was working out the smallest ant man could possibly go, because if ant man shrinks by shrinking space between atoms it is physically impossible for him to go subatomic.
If you’re interested, the smallest size the average human male could be shrunk via ant mam technology, according to my brother, is 0.018 cm.