Wood-burning stoves cause almost half of cancer risk from urban air pollution – study | Air pollution



Wood stoves in urban areas are responsible for nearly half of people’s exposure to carcinogenic chemicals in air pollution particles, new research shows.

Polycyclic aromatic hydrocarbons (PAHs) contained in tiny pollution particles are produced by the combustion of fuels and have long been known to have carcinogenic effects. The new study examined the sources of PAHs and found that burning wood produced more than diesel fuel or gasoline used in vehicles.

The scan was carried out in Athens, Greece, but the researchers made it clear that this was not an unusual case. They said home wood burning is a significant problem for urban air quality across Europe and that excessive exposure to wood smoke can have serious health effects.

“Athens is no exception – it’s more representative of a rule,” said Athanasios Nenes, of the Hellas Research and Technology Foundation in Patras, Greece, and the Federal Polytechnic in Lausanne. , in Switzerland, and one of the team members behind the new study. “On the one hand, it’s, ‘Oh, my God, this is terrible.’ But on the other hand, it indicates something that people can actually do to reduce this risk without much effort. You basically stop burning wood. It is essential.

Research published last year showed wood burning in homes is the biggest source of small particle air pollution in the UK, producing three times more road traffic, despite only 8% of the population using wood stoves.

Even new wood-burning stoves meeting the “eco-design” standard still emit 750 times more fine particle pollution than a modern heavy-duty truck. Wood stoves also triple the level of harmful pollution inside homes and should be sold with a health warning, scientists say.

The new research, published in the journal Atmospheric Chemistry and Physics, took background samples of the air in Athens every day for a year. These were analyzed for 31 PAHs and a wide range of other chemical markers.

Specific compounds are associated with different sources of pollution and these have enabled scientists to calculate the proportion of PAHs produced by each source. They found that 31% of annual PAHs came from burning wood, mainly in winter, 33% from diesel and petroleum, and 29% from gasoline (gasoline).

However, some PAHs are more carcinogenic than others, and when this was taken into account, the proportion of cancer risk to humans from wood combustion was 43%, with diesel and 36% fuel oil and 17% gasoline.

“We know that [smoke from] burning wood is much more toxic than other types of particles, ”said Nenes, and the results clearly point to burning wood as the main long-term carcinogenic risk factor.

The level of PAH pollution in Athens was on the same order of magnitude as that found in studies of other European and North American cities, the researchers said, with much higher levels typically reported for Chinese cities.

The average annual PAH concentration in the Athens study was below EU limits but doubled the World Health Organization reference level. Based on WHO data, PAHs in Athens are expected to cause 5 more cancer cases per 100,000 people, the researchers said.

“Given [the carcinogen exposure] and prolonged use of [wood] burning across Europe, for example in France, Germany, Ireland and the UK, European action and policies aimed at regulating [wood] combustion emissions are needed immediately, as they can lead to considerable public health benefits, ”the scientists said.

Nenes said PAHs were not the only carcinogen in wood smoke, and they also contained many other compounds that were harmful to health. “Wood smoke is particularly potent and causes all kinds of illness, from cancer to oxidative stress, which leads to heart attacks and strokes, obesity, premature aging, diabetes – everything to do with it. inflammation in the body. So overall I’m really worried about the burning of wood.

Gary Fuller from Imperial College London, who was not part of the research team, said: “We tend to think of burning wood to be somehow harmless because wood is a natural product. These measures remind us that burning wood is not without pollution. UK data on emissions of benzo (a) pyrene, one of the main PAHs, shows a 16% increase since 2000 from home wood burning.

Professor Alison Tomlin of the University of Leeds, UK, said the switch to electric cars will reduce exposure to PAHs from traffic. “However, unless appropriate mitigation methods are developed to reduce PAH emissions from domestic wood burners and boilers, they will continue to pose a significant health risk.” she said.

The Athens study showed that much of the exposure to PAHs occurred on winter days with little wind and rain, meaning the wood smoke did not disperse . Tomlin said implementing “no-burn days” at these times could be a useful short-term measure. “However, enforcing such a policy, or even broader restrictions on wood burning in densely populated areas, could be difficult,” she said.

Earlier in December, the council of Utrecht in the Netherlands announced grants of up to € 2,000 (£ 1,700) to encourage people to replace their wood-burning stoves and fireplaces in order to clean the air from the city.

Previous research by Nenes and colleagues found that wood smoke emitted at night oxidizes to more harmful compounds much faster than expected. This means that the pollution becomes more dangerous to health as long as it is still concentrated near the source, rather than oxidizing in a few days by dispersing.



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