A domestic chimney spews dark smoke in Głuchołazy. About 50% of air pollution in Poland is caused by residential heating , with 13% from vehicles. Most of the smog plaguing the country is caused by domestic burning of low-quality coal, wood and even rubbish in the stoves that at least a third of households use. These devices emit carcinogens such as benzo(a)pyrene. White smoke represents the correct use of domestic furnaces; darker plumes mean either rubbish or another chemical fuel is being burnt. Concerned residents have been reporting sightings of non-white smoke to the authorities