I put the space heater away last week. It had been a couple of weeks since the furnace's "fresh-air" system had sucked in smoke from the neighbor's fireplace. So what just happened when the furnace kicked on? Yes. So now my throat itches and I have a sudden headache, and I've had to turn the furnace way down, close my heating vent, put my air filter on high, and drag out the electric heater. Bleeping caveman neighbor and his polluting fire.