Since when are neutrinos and 'air' molecules tangible?
There are actually subatomic particles that come down with huge speeds, sometimes .9 C and go right through you. They also go through the earth. Muons for example. They are created when photons from space(sunlight) hit the atmosphere. But they decay pretty fast. They have speeds of .9 C so they have time dilation.
All those objects will go right throught you. Remember an atom is one tiny point and then a large space around it with electrons moving around. So its mostly nothing. Same with molecules, its mostly empty. So the chance that those small particles hit each other is very small. And if it happens they will just bumb and still nothing would happen.
Of course, when it happens alot you do get sick. They call it radia-activity

But those particles don't have much energy. A baseball moving 30 m/s has lots of more energy.
The question is, can a grain of sand get enough energy to kill you? And does the brain absorb the energy. When I talked about shock wave I wasn't talking about a sonic boom. I was wondering if the brain would absord the energy of the grain of sand. It happens with some bullets. They give bullets special shapes so they create nasty wounds and don't just go through creating small clean wounds(or the opposite for armored targets).
Maybe it depends on the shape of the grain of sand too.