Scientists review casts doubt on impact of wood burning stoves

Scientists review casts doubt on impact of wood burning stoves

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Non-profit industry organisations HETAS and Woodsure say a scientific review of air quality measures casts serious doubt on the claim that wood burning causes more pollution than traffic.

The independent scientific review1, commissioned by HETAS, draws attention to the uncertainty around how much domestic burning contributes to UK air pollution. In fact, the government report published this month using National Atmospheric Emission Inventory (NAEI) data for UK air pollutant emissions statistics admits that the methodology for estimating the real impact of domestic combustion is uncertain2.

The Clean Air Strategy 2019 currently attributes 38% of UK particulate matter emissions to the domestic burning of solid fuel, which many have understood refers to wood burning stoves. However, scientists now believe this has been overestimated and is misleading because it does not distinguish between different burning sources.

Dr Edward Mitchell, independent consultant and co-author of the scientific review, says:

The evidence is clear that the government estimates for the contribution of domestic burning to UK air pollution are based on a number of flawed assumptions and poor data sources. Our report delves deeply into the data sources used in the NAEI and concludes that the 38% contribution figure is highly inaccurate.It is important to acknowledge that domestic burning does contribute to air pollution, but to suggest that the contribution is nearly 40% of PM2.5 over the whole year for a source that is only prevalent in the winter is extremely unlikely. Our report investigates where the NAEI’s emissions factors come from and found that they were based on very old data for old stoves that weren’t specific to the UK. Thankfully, DEFRA is looking to commission a new piece of work to improve the accuracy of these factors for UK stoves, so it will be really interesting to see the updated figures. Emissions factors can change hugely between the more polluting sources such as open fires burning wet wood to modern Ecodesign compliant appliances, which emit up to 80% less PM2.5. New stoves must adhere to increasingly strict emissions criteria and smoky fuels such as coal and wet wood are being banned. Now we must turn our attention to other domestic burning sources such as barbecues, smokers, fire pits, chimeneas, garden incinerators and bonfires. The rise in sales of cheap outdoor burners from discount supermarkets is a major threat to air quality.

HETAS commissioned the review to understand current emissions estimates and highlight the need for more accurate information. This will help the industry and government to prioritise resources and take action to reduce emissions from the most polluting sources.

The review also says that without accurately defining the highest contributing sources and taking targeted action, the UK will not meet the 2030 emissions reductions obligations of the NEC Directive.

Bruce Allen, CEO of HETAS and Woodsure, explains:

Air quality is an enormous area of focus for us. At HETAS we help by certifying approved and less polluting appliances, fuels and tradespeople in the industry, but there is much that is outside of our influence at the moment. We really need to look at what the science is telling us about particulate pollution so we, as a country, can hit our emissions targets. One of HETAS’ most important roles is helping people understand how to reduce the impact of burning at home. There are practical steps that can be taken immediately to reduce carbon and particulate emissions in the home by up to 90%, compared to burning coal in an open fire. Using only high quality, sustainable and renewable fuel, like pellets or Ready to Burn certified wood that has up to 20% moisture content, will improve fuel efficiency, air quality and reduce greenhouse gas emissions. Keep your wood burning or solid fuel appliance well maintained and always use a HETAS certified installer or sweep. You can find competent tradespeople along with easy-to-understand and reliable advice on the HETAS website. If you can, replacing old stoves or open fires with modern Ecodesign compliant appliances, which are designed to burn with less smoke, is one way to greatly improve air quality.

The Ready to Burn certification scheme is backed by the Government’s Department for Environment, Food and Rural Affairs (Defra) to support The Air Quality (Domestic Solid Fuels Standards) (England) Regulations 2020 which come into force in England on 1 May 2021. This new law restricts the sale of wet wood sold in volumes under 2m(i.e. two dumpy bags) and makes it easier for consumers to identify and buy dry wood that’s certified as Ready to Burn and therefore ready for immediate use without further drying.  Where consumers buy their fuel in bulk, suppliers will be required to provide an advisory notice that the wood requires further drying before use.

To find out more visit https://www.hetas.co.uk/understanding-the-impact-of-domestic-wood-burning/ or email hello@hetas.co.uk to request a copy of the full report.


1 A Review of the Impact of Domestic Combustion on UK Air Quality by Mitchell, E.J.S, Cottom, J.W., Phillips, D., and Dooley, B. Published September 2019.

2https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/959858/Methods_and_quality_processes_for_UK_air_pollutant_emissions_statistics_v1.2.pdf 


For further information visit www.hetas.co.uk or to find out more about Woodsure and Ready to Burn certification visit www.woodsure.co.uk and www.readytoburn.org


For media enquiries for HETAS and Woodsure contact: Rachel Meagher at Target on 07920 468412, rachel.meagher@targetgroup.co.uk