London was once periodically plagued by waves of choking smog, as Londoners burned dirty fuel to keep warm. That was until 1956, when a series of clean-air acts started to bring toxic air pollution under control. Measures including a ban on coal-burning in the city and restrictions on chimney heights helped transform the city formerly known as the “Big Smoke” into a more liveable – and breathable – environment.
However, new research suggests that those decades of progress have gone into reverse. In January 2023, data tracked by Imperial College London found the capital’s air pollution had risen to its highest level in six years. Particulate analysis found that between 60 per cent and 70 per cent of this pollution came from one source: wood-burning.
PM2.5 is the metric used to measure one of the most toxic forms of pollution that wood burners emit: sooty particles that can enter the bloodstream and become lodged in organs, causing cardiovascular and other health problems. It is on the increase: UK emissions data published this week showed PM2.5 pollution from domestic wood-burning increased by 124 per cent between 2011 and 2021.
That means home heating is now responsible for 27 per cent of particulate pollution, producing more PM2.5 than any other source, including transport (13 per cent) and industrial usage (26 per cent). Overall, PM2.5 particulate pollution increased 6 per cent between 2020 and 2021, reversing a trend in which levels declined 85 per cent between 1970 and 2021.
Cost-of-living crisis
The boom in dirty home-heating is also reflected elsewhere. Stove Industry Alliance data seen by the New Statesman shows that some 200,000 wood-burning stoves were sold in the UK in 2022, close to twice the amount that were sold in 2020. These stoves only represent a fraction of the market: many people burn wood in older fireplaces; a third burn wood on open fires. In fact, every London borough records an average level of PM2.5 that is significantly higher than the 5 micrograms per cubic metre that the World Health Organisation advises is safe.
“Reports of increased pollution levels are concerning,” said Maureen Talbot, head of clinical support at the British Heart Foundation, “because we know that air pollution can increase everyone’s risk of developing heart and circulatory diseases, as well as exacerbating existing cardiovascular conditions.”
Tim Dexter, clean air policy manager at Asthma and Lung UK added that his organisation is now “encouraging people to not use wood burners, especially if you have a lung condition, and to consider using cleaner fuel options”.
There is a perception that wood-burning stoves are luxury items favoured by the upper classes, but experts have warned that the cost-of-living crisis is a major reason for the recent surge in wood smoke pollution. “There is a link between domestic solid-fuel burning and fuel poverty,” a spokesperson for the Chartered Institute of Environmental Health (CIEH) told me. “There is a balancing act that the government must take with respect to promoting environmental protection while preventing households from experiencing undue financial hardship.”
As was the case during the days of London’s great smogs, it seems pollution is once again driven by the unaffordability of mains heating: the latest energy price data from February 2023 shows that a modern wood-burning stove costs 71 per cent less per kilowatt-hour than electric heating, and 12 per cent less than mains gas.
Rising pollution
Jemima Hartshorn was on maternity leave while living on Coldharbour Lane in Brixton, south London when she became concerned that an air pollution monitor on her road was regularly indicating that pollution was far exceeding healthy levels. She founded the activist group Mums for Lungs to try and address the problem. “The science is completely clear,” she said. “We cannot be worried enough about these air pollution levels. Rising wood smoke levels are completely unacceptable in a highly populated city like London. Wood burners should be banned from within the city.”
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Other members of Mums for Lungs agree. “I’m getting a smoker’s cough every morning when households around me are burning wood,” said Diana, also from south London. “Wood-burning has been normalised and celebrated in the UK in the built environment.”
“We live on a very busy road with cars, motorbikes and buses often queuing down the road. The smell comes down our own chimney and lingers outside our house,” added Maria, also from London. “Wood-burning on top of all of this really makes me feel desperate to live in a less polluted area to bring up my children.”
Failed policies
Policies designed to limit air pollution from burning wood in cities have largely proved ineffective. The Clean Air Act of 1956 first introduced smoke-control areas (SCAs), which ban households from emitting smoke from their chimneys. Nearly the whole of London is now an SCA, but it has been “notoriously hard to prove breaches are taking place beyond a reasonable doubt”, the CIEH spokesperson said.
One major problem is that if households are burning wood at night, it is hard to see the smoke. Local authorities also lack the resources to effectively respond to all complaints. The University of Nottingham researcher James Heydon found that of the 2,524 complaints received by a sample of 30 councils between 2014 and 2020, only two had taken court action. Research from Mums for Lungs has also found that just 19 wood-burning penalties had been issued by English councils in the six years to 2021, out of more than 18,000 complaints.
There are also rules over the dampness of wood allowed to be burned, which critics say are impossible to enforce, as well as the requirement since January 2022 that all new wood-burning stoves meet Ecodesign standards. Research shows even these stoves produce 465 times more toxic pollution than central gas heating.
The latest move from the UK government, announced in February, is to ban wood-burning stoves from new and refurbished buildings, which may help to alleviate the problem. But organisations like CIEH are calling for a mass rollout of targeted, energy-efficient measures as a more effective means of addressing the root economic causes – by allowing low-income families to heat their house more cheaply.
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