When wood is burned, harmful substances are released, such as particulate matter, PAHs and benzene. The smoke is unhealthy for everyone, but especially for people with respiratory diseases, cardiovascular diseases, the elderly and children. The advice does not only apply to the province of Utrecht, but also to Flevoland, Gelderland, Drenthe and Overijssel. People who only have a wood stove to heat their home can also ignore the advice.