The Optimist | The Air We Breathe

What impact do wood burners have on our health?

They seem natural but a wood-burner can emit more polluting particles than a diesel lorry, say scientists

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Matt Writtle
Nicola Slawson
19 October 2020

When Rebecca Stevens was buying her home in Barnes six years ago it already had a wood-burning stove installed. But while many home-buyers would have been thrilled by the addition — some 1.5 million stoves have already been fitted in Britain, with 200,000 being sold annually — Ms Stevens only uses it about four times a year.

“It does look nice when it’s on because of the brightness that comes from it,” says Ms Stevens, a freelance nutritionist.

“But I am also aware of the contribution towards air pollution, and so I only use it when it’s a necessity.”

She burns briquettes made from recycled sawdust because they are cleaner. Like many Londoners, she is concerned about the air her children breathe despite living with her husband and three children in what is perceived to be a leafy part of London. “We’re in Zone 3, but it’s still a worry,” she says.

“However, I’m still more concerned about air pollution from traffic rather than wood-burners. I would say that especially with the closure of Hammersmith Bridge, it is really bad around here.”

While emissions from vehicles and industry remain the biggest causes of air pollution, wood-burning is a growing concern for experts who have noticed the impact of the increasing popularity of stoves and open fires on our already dirty air.

When wood is burned, it releases harmful pollutants, including tiny particles known as PM2.5 which are easily inhaled and can enter the bloodstream. Of all pollutants, this particulate matter has the most significant impact on our health, linked to heart disease, strokes and cancer.

Almost two-fifths (38 per cent) of PM2.5 in the UK comes from domestic wood-burners and open fires, according to research from the Department for Environment, Food and Rural Affairs. And while particle pollution from traffic and industry is expected to decrease, thanks to increasingly strict measures, wood-burning looks likely to offset any improvements, explains Dr Gary Fuller, of the London Air Quality Network at King’s College London.

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The Air We Breathe is a year-long project that considers the impact of London’s air on our health and asks how we can take action to limit it.

This project is supported financially by the Children’s Investment Fund Foundation, Guy’s & St Thomas’ Charity, and the Clean Air Fund, who share the project’s aims, but our journalism remains editorially independent.

This project is part of our Future London initiative, which looks for solutions to some of the biggest issues facing the capital.

By 2030, particle pollution in UK cities is not expected to have reduced overall, according to a study by Dr Fuller’s colleagues at King’s College. This is despite its effect on health.

“Globally, breathing PM2.5 is one of the largest risk factors for an early death,” says Dr Fuller. “Around four million people die early from breathing PM2.5 across the globe — around 400,000 in Europe, and nearly 4,000 in London.”

When Barney Scott, 30, moved to London from Bristol for a tech job two years ago, he bought a houseboat that came with an oil stove as its source of heating. Initially, he thought that he’d change it for a wood-burning or multi-fuel stove. But then he started to research the implications of burning wood. “There’s a bit of a prevalent attitude among the population in general, that burning wood is fine because it’s not a fossil fuel,” he says.

“I think that is equating air pollution with carbon emissions.

“In the case of wood-burning stoves, it’s the impact of particulate emissions from burning wood that I found was really significant. I was pretty astonished by it.”

Instead, Mr Scott chooses to continue to burn kerosene, which still emits carbon dioxide and other gases into the environment but is cleaner-burning than other fossil fuels. He has also installed solar panels on the roof of his boat.

Dr Fuller echoes Mr Scott’s experience. People don’t just use wood-burners because they’re Instagram-friendly, and lovely for warming your toes, he notes.

Lighting a fire is perceived as something “natural”, he says, particularly when compared with alternatives: “There is the worry of climate change, and wood is perceived as being carbon-neutral.”

The damage to our health is, however, only just beginning to be fully and widely understood. According to a global review published in 2019, almost every cell in the human body can be affected by polluted air.

Scientists from the Forum of International Respiratory Societies concluded that air pollution could be linked to heart and lung disease, diabetes, dementia, liver problems and even to brittle bones and damaged skin. It can also affect fertility and foetuses and children, the review found.

A separate study by researchers at University College London, also published last year, found that people living with air pollution have higher rates of depression and suicide.

In October, the Government moved to curb the impact of wood-burning with a series of measures including changes to existing smoke control legislation, and allowing local authorities to take action in high-pollution areas.

The draft Environment Bill also includes plans to prohibit the sale of the most polluting fuels and ensure that only the cleanest stoves are available for purchase by 2022 — although even these stoves release significant amounts of harmful pollutants into the air, says Dr Fuller. According to his 2017 research, a new stove can produce about six times more particle pollution per hour than a modern diesel lorry, or 18 times more than a modern diesel car.

Last year the Government also indicated that boat owners would no longer be exempt from the Clean Air Act, which limits what can be burned by households, but has yet to give any details. That’s concerning for London’s houseboat dwellers — a community that has grown dramatically as house prices in the capital have soared, and who rely on their stoves as the only way they can heat their homes.

While Mr Scott was able to keep his oil stove, many boat-owners do not have that option — and replacing a wood-burning stove can be expensive.

“There are a lot of boaters with very limited means and I would say they rely most on wood,” Mr Scott says. “When the topic comes up on forums and Facebook groups, there is always a very mixed response. Many will be justified in saying they don’t have a choice. Getting a new stove installed is very expensive.”

Peter Birch, environmental policy adviser at the Canal and River Trust, says any changes to legislation need to take the circumstances of those who live on boats into account.

“If it was just as simple as buy smokeless fuel, then it wouldn’t be a problem,” he says. “But if people will actually have to buy a new stove and possibly do a whole load of other stuff in order to comply, then our concern is that we’re setting people up to fail.”

Jemima Hartshorn a founder of Mums for Lungs
Adrian Lourie

For other Londoners, a wood-burner can be more of a choice than a necessity. Jemima Hartshorn, who founded the campaign group Mums For Lungs in 2001, thinks that wood-burners continue to be popular because many people are unaware of the issues.

“It’s partly because humankind has always warmed themselves by a fire and there’s something comforting about it,” she says. “I have total sympathy for people who say wood-burning stoves are lovely and cosy.”

However, burning wood affects not just the air quality inside your property, but also the air quality around it. Even if no one in your neighbourhood has a wood-burning stove, particle pollution is difficult to control, and depending on the weather, the wind may blow the dirty air to a different area completely.

Ms Hartshorn asks that before lighting a fire, people think about vulnerable people in the neighbourhood and beyond — including children, the elderly, and those with lung conditions — who might be affected by the pollution. “People have to think about their priorities,” she says.

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