A truck hauling sand was on the road in front of me, a motorcyclist was in the lane to my right. The biker had sunglasses and gloves, but no helmet. As I pulled alongside him, I noted that his hand was up in front of his face and I thought he might be shielding himself from the wind.
As I had pulled in behind this truck a couple miles back, I was pleasantly surprised that it was throwing off exactly ZERO rocks or sand back to my car. There was a stiff wind from left to right across the highway.
I pulled in front of the motorcyclist and realized that the sand I had expected to blow off behind the truck was blowing off to the right of the truck. The biker was keeping sand out of his mouth/nose.
You know what else keeps sand out of your nose? A full-face helmet. Those also do a handy job of keeping your brains and bits of skull out of the cracks in the highway.
If you voluntarily ride a motorcycle with no helmet in a non-emergent situation, you are an idiot.