I wonder what the difference between PM2.5 from cooking oil or fat vs PM2.5 from combustion engines is on the lungs.

My instinct is that it should be less toxic from vegetable oil, if it's just vaporised... past the smoke point maybe the chemistry changes enough to make it more toxic. The body has mechanisms to remove foreign matter from the lungs, but how easily and how much it clogs up your lymph nodes seems to depend on what it's made of.