Silicosis is no laughing matter. Sandblasters, miners and such can really suffer from it if they don’t diligently use a good respirator around airborne rock dust. Sand passing by in a rail car seems unlikely to offer the same risk but I would not dismiss it out of hand.
I would.
Do you think passing by in a rail car a few times a day comes anywhere close to the exposure of people living at the beach or in the desert?
Big difference between wet natural sand grains and dry nano-sized dust. It is like comparing an elephant to a bacterium.