Wood-burning stoves are in fashion but cause serious pollution

CHRISTMAS 2016 was hygge’s moment in Britain. A crush of books appeared seeking to explain how Danes—for the word is theirs—achieve hygge, which means comfort or convivial ease. An important ingredient, say the books, is a wood fire, around which one is supposed to sit, sipping something warming. British readers ought to have been prepared for that. A surprise publishing hit of 2015 had been “Norwegian Wood”, a book that teaches how to chop and dry firewood.

About 175,000 new wood-burning stoves are sold in Britain each year. In 2015 an official survey found that 7.5% of Britons burn wood at home, usually to provide a little extra heat (most wood-burning households have central heating) or because they like looking at flames. Wood-burning is fashionable and seemingly environmentally friendly, since trees can be replanted. It is also, unfortunately, a big contributor to air pollution in Europe.

Gary Fuller of King’s College, London, an air-pollution expert, has calculated that wood-burning is responsible for between 23% and 31% of all the fine particles generated in the cities of Birmingham and London. These particles, which are less than 2.5 micrometres (thousandths of a millimetre) in diameter, are blamed for various respiratory diseases and lung cancer. In fact, pollution from wood-burning seems to be falling gently, despite the rush to install stoves—perhaps because new stoves are cleaner than old ones, and much cleaner than simply burning logs in a fireplace. But that is still a lot of smoke.

In hygge’s homeland things are even worse. “If you ask Danish children to draw a house, they will draw a chimney with smoke coming out,” says Kare Press-Kristensen, an adviser to the Danish Ecological Council. Domestic wood-burning supplies about 3% of Denmark’s energy consumption but accounts for 67% of fine-particle emissions. Unlike, say, a coal-fired power station, domestic wood-fires discharge pollutants straight into populated areas, and they do so at times of day when people are at home. Unlike other fuels, wood is untaxed in Denmark. Wood-burning increased 2.5 times in 2000 to 2015. Green-minded Europeans keen to change behaviour in poor countries might first sniff the air closer to home.