into my lungs, how is it that it does not accumulate in my lungs and kill me. Am I risking my life my siiting in the back of a pickup truck on a dusty backroad breathing in the dust? Am I risking my life breathing in water mist when I spray my plants?
I can’t see why water would be bad. You breathe water vapor all the time and, in fact, it is dry air that is not good. The dust and other particles are supposed to be filtered by your nose but it can only do so much so if you are in a dusty environment you should wear a filtering mask.
Yes, but you’ll be lucky if it’s the dust that kills you. 
-j
I lived in Phoenix for many years just outside the city limits its dusty as hell. Unbelievably dusty. As a matter of fact I’ve seen Dust storms 10-15 thousand feet high 20 miles across and…it sucks.
I would not worry about the water vapor, but the dust, be careful. Wear a bandana.