The warning comes from the head of fire and rescue services in the west of the country, who says that the "worrying trend" is a recipe for disaster, national broadcaster Yle reports. While sauna is a national obsession in Finland to the point that Suomi Post issued a set of sauna-related stamps , some Finns would rather put the space to other uses, it seems. There are thought to be two million saunas in the country, bringing warmth to a population of 5.4 million.