They're probably doing illegal things. Ask at your town hall. Here in the middle of westcountry-nowhere no-one gives a damn. We burn mostly smokeless fuel, though we don't have to (Homefire Ovals is what we buy), topped up with a bit of wood that I've cut meself and dried for a few months. Burning wet or unseasoned wood, or cheap coal, is bad news not only for the environment but also for your chimbley.