Modern coffee roasters don't expose the workers to the smoke. They have a big box mounted to the side of the roaster called the after burner. It filters the air

Modern coffee roasters don't expose the workers to the smoke. They have a big box mounted to the side of the roaster called the after burner. It filters the air that comes out of the roaster to remove the chaff (basically the thin paper that covers the bean). It then passes the air through a large heating element that finishes burning any particulates (A tiny coffee roaster's after burner draws 50 amps at 220 volts, or 11000 watts. A small space heater draws around 1500 watts, for comparison). This hot air is then either piped outside through a vent, or passed through the beans again to help them roast. Then, when the beans come out, they land on a grate with a stirrer. A large fan sucks air past them, and also blows it outside. There is very little smoke put into the room, basically only when the beans are falling from the roaster into the stirrer. It's a large, expensive, relatively complicated computer-controlled machine with the main goal of eliminating smoke. From my understanding of this research, they're saying workers are being exposed to harmful pollutants despite all of this equipment to reduce emissions. And in all my time repairing coffee grinders, I have never noticed a significant amount of fine dust. Coffee is actually a little oily, so any fine particles turns into a thick buildup that's a huge pain to remove.