Turning up the heat on indoor air quality

Wood-burning stoves are a significant emitter of PM2.5 in the UK – but is a lack of knowledge of how they impact the environment fanning the flames of air pollution?

Winter is approaching and many people will be looking forward to putting their feet up and sitting down in front of a roaring fire or wood-burning stove.

The popularity of stoves over recent years has rocketed, and, according to the industry body HETAS, the number of stove registrations increased 10-fold in the decade between 2004 and 2014, from 12,000 to 130,000 a year.

For many, wood-burning stoves are a more natural, and environmentally friendly way to heat their homes, but the government’s own statistics show that burning wood and coal in open fires and stoves account for more than a third (38%) of the UK’s primary emissions of PM2.5, compared to industry and road transport, which contribute 16% and 12%, respectively.

Public perception

Given the contribution home stoves and fires can make to air quality, it seems strange that it is not higher up the agenda for both central and local government. Beth Gardiner, the author of Choked, The Age of Air Pollution and The Fight for a Cleaner Future, says there is a ‘huge gap in perception and public understanding around wood stoves’. ‘People enjoy curling up in front of the fire,’ she tells Air Quality News.

‘It’s been promoted as a clean, climate-friendly way to heat your home, but I think that’s highly questionable and I see a parallel with the diesel car mess that the UK and Europe has gotten itself into.’ ‘Diesel was promoted in the early 2000s as a climate-friendly fuel and we are seeing the same thing with wood. You can even get tax incentives under the Renewable Heat Incentive, which encourages people to convert their home heating to wood, instead of gas.’ ‘But no one acknowledges the health cost and the climate benefit is also very questionable.’ The government did include wood-burning stoves as part of its Clean Air Strategy, which was published in January, by the then environment secretary, Michael Gove.

The strategy included commitments to ban the sale of the most polluting fuels, ensure only the cleanest stoves are available on the market by 2022 and give new powers to local authorities to take action in areas of high pollution. In its upcoming Environment Bill, the government has said that it will give local authorities extra powers to tackle air pollution from wood but Professor Roy Harrison from the University of Birmingham, adds a note of caution about the government’s plans.

‘The report of Defra’s advisory committee, the Air Quality Expert Group, makes clear its concerns over the increased use of wood stoves because of their major contribution to particulate matter pollution of the atmosphere, which is of a similar magnitude to traffic pollution by fine particles,’ says Prof. Harrison.

‘Defra’s intention to legislate for cleaner fuels (only dried wood) and for better designed, lower emission stoves is to be welcomed, but will take a long time to generate impact due to the very slow rate of renewal of old stoves, and the continued installation of newer, albeit less polluting stoves.

Planning ahead

In the meantime, many local authorities are developing their own clean air strategies. Some plans, like those of Southampton City Council, do not contain any specific actions or targets around wood-burners, while others, like Cornwall Council, are addressing the issue in their draft proposals.

Cornwall’s draft clean air strategy, which was published in July and due to go to consultation this autumn, looks to raise awareness of air pollution among residents by discouraging drivers from idling and sharing advice on reducing pollution from wood-burning stoves.

It also contains information on sources of indoor air pollution in homes and workplaces and how to reduce it, for example from cleaning products, furniture and cooking, all of which can affect health.

The London Borough of Camden’s clean air action plan for 2019-2022 includes a commitment to ensure that Smoke Control Zone regulations are communicated and enforced with the support of residents’ associations.

According to the document, domestic open fires and stoves account for 4% of Camden’s total PM10 and 7.2% of PM2.5. It adds that the figures for 2019- 2022 are expected to be higher.

Camden will also look at whether local by-laws could be introduced to ban the use of fireplaces and wood-burning stoves. The document also states that it plans to lobby government to tighten smoke control regulations and ban the use of fireplaces and wood-burners in areas well served by cleaner heating sources.

Regulations

A spokesman for London Councils says regulations around wood-burning stoves currently falls under the remit of each individual borough. ‘However, solid fuel burning produces a significant amount of particulate matter in London, which has negative impacts on the health of residents across London,’ adds the spokesman.

‘For this reason, we believe that local authorities need improved powers and increased resources to effectively tackle emissions from solid fuel burning, including woodburning stoves.’

Earlier this year, Bristol mayor Marvin Rees also called on the government to give councils increased powers to ban private wood-burners. ‘The government must give us the powers to say no to pollutants, especially in heavily populated areas,’ said Rees in June, in a speech to mark Clean Air Day.

Gardiner agrees that, when it comes to tackling the issue of wood-burning stoves, national action is required. ‘When you talk about traffic, part of the mistake that’s been made is that we leave it to cities and towns to deal with on their own,’ the author tells Air Quality News.

‘Camden can block certain roads, but Camden or any other local authority cannot control the fact that Volkswagen and other car manufacturers are still selling diesel cars.

‘It’s more than a local authority has the power to deal with,’ she adds. ‘The problem with wood stoves is similar. We’re leaving it to the localities to deal with it on their own, but it needs to be addressed at a national level if you are to see any significant improvement.’