Arsenic particles are being spotted by scientists in London’s air, as concerns grow that people are increasingly burning waste wood from construction sites while being unaware of the serious health risks. Dr Anja Tremper at Imperial College London’s air research station in south London tracked January’s data and found arsenic particles in London’s air, especially around the weekend of 2223 when air pollution reached the top index value of 10 on the UK government’s scale. Tremper said: “This is part of a long-term pattern. When I investigated the pollution sources in the 2019 and 2020 dataset, I also found arsenic among the chemicals from wood smoke.” Despite clear messages from government and local councils, a survey for the Department for Environment, Food and Rural Affairs in 2018-19 revealed that about 9% of people who burned wood at home were burning waste wood. The problem is that construction wood is normally treated with arsenic-based preservatives to protect against insects and fungi. This arsenic becomes part of the ash and smoke when the wood is burned. The survey found examples of people burning fence panels, pallets, old furniture, doors, door frames and construction wood salvaged from skips. One woman described how her husband collected waste wood from skips using a wheelbarrow. Many people in the survey did not know what types of wood might be treated and others justified their behaviour as harmless because they only did it occasionally. Another mistakenly thought their Defra-approved stove would remove any toxins. And this problem is not isolated to London. Dr James Allan, who operates Manchester University’s air research site, said: “We see arsenic in Manchester as well, associated with cold weather and the black carbon that you get from wood-burning.” In Auckland, New Zealand, scientists have been investigating if people in the city were being exposed to arsenic from wood-heating. Many New Zealanders pride themselves on finding and burning free wood. Despite official warnings, almost 20% of homes routinely burn construction wood. This can lead to airborne arsenic concentrations that are double the UK and EU legal limits. As part of the research, 30 men were asked to grow beards for two weeks, then shave and collect the hair for analysis. Arsenic in their bodies would be incorporated into their growing beard forming a record of their exposure. Aside from cigarette-smoking, the biggest factor that affected arsenic in the men’s beards was the frequency of wood-burning smells in their neighbourhood, suggesting that nearby wood-burning was a main exposure route. More arsenic was also found in the beards of men who burned wood offcuts, so arsenic from their wood burner could be a problem too. The New Zealand study looked at exposure only and not the men’s health. However, the American Medical Association reports an extreme case of arsenic poisoning in family that burned construction wood to heat their home. As well as breathing arsenic-laden smoke, ash and dust from their fire was thought to be a significant exposure route. Over three years, their symptoms included neurological problems such as blackouts and seizures experienced by young children, as well as skin and breathing problems including the hospitalisation of one child and wintertime hair loss. The UK government began measuring arsenic air pollution in 2003. Annual average concentrations fell until 2008, as coal-fired power stations closed, but have been relatively flat for more than a decade. Reassuringly, they have been less than 20% of the maximum values set in UK and EU law but the sampling points in this network are not designed to detect neighbourhood-scale impacts from residents who burn waste wood, nor air pollution inside these houses. During the Greek financial crisis, many people turned to burning waste wood and old furniture to heat their homes. This led to increased wood burning pollution along with arsenic and also lead from old paint. We are waiting to see if the current high energy prices and cost of living crisis is leading to more people burning waste wood across the UK and Europe.