We have a wood stove. We haven't used it much for a couple years; but when we did, we did our best to let our wood dry out for a year before burning, and also to keep our fires hot and well oxygenated. As such, you generally wouldn't see smoke coming out of our chimney, just hot air. (That still releases some particulates, I realize)
But a lot of people around here burn wood that's been cut fairly recently, so it still contains a lot of moisture. On top of that, they often manage room temperature by damping - limiting the air flow to the fire . Both practices throw huge amounts of smoke/particulates into the air. I always cringe when I go by a house with smoke belching out the chimney as if it were an old coal-burning freight train.
People bitch and moan about the government meddling in their homes, but in this case it's their own fault. We all have to breathe that exhaust.