In a world grappling with multiple crises, where thousands face fuel poverty, wood-burning stoves have emerged as a lifeline for many families. It's concerning and misleading when certain publications misrepresent data to criticise a heat source that has been instrumental in helping these households.
While we acknowledge that upgrading outdated open fires and wood-burning stoves can significantly reduce PM2.5 emissions, we urge a closer examination of the data, which highlights the role of modern ultra-efficient stoves in addressing this issue.
The UK's Clean Air Strategy from Defra points out that domestic combustion is responsible for 38% of fine particulate matter. However, this statistic was derived from a 2015 government survey, which overestimated wood consumption in stoves and fireplaces.
A more extensive and independently verified survey conducted in 2019, involving over 10,000 participants, revealed that the actual contribution of domestic combustion, including wood-burning stoves, was only 13%, rather than the initially estimated 38%. Moreover, this figure did not account for the fact that new Ecodesign stoves emit 66% less emissions than previously estimated.
It's essential to recognize that the category of domestic combustion encompasses various sources, including bonfires, garden incinerators, outdoor pizza ovens, and even wildfires. Therefore, attributing all PM2.5 emissions to wood-burning stoves alone is an oversimplification.
Indoor PM2.5 Levels
PM2.5, or fine particulate matter, poses health risks when inhaled in substantial quantities. The World Health Organisation (WHO) recommends a daily average PM2.5 limit of ≤ 10 µg/m3 for outdoor air. To provide context, Central London's air quality typically ranges from 18-25 µg/m3.
A 2019 study in the US, featured in the Journal of Exposure Science & Environmental Epidemiology, examined 137 homes. It found that homes with wood stoves had an average daily PM2.5 level of 6-8 µg/m3, only slightly higher than the 6-7 µg/m3 in homes without wood stoves. These differences fall well within WHO's safe levels.
This data aligns with the understanding that well-functioning wood stoves effectively remove air, smoke, and particulates from indoor spaces. However, proper wood-stove practices are crucial for maintaining low PM2.5 levels, a message we're passionate about conveying to our customers and fellow wood-stove users.
Outside the Home
Comparing emission rates between wood stoves and heavy goods vehicles (HGVs) has raised concerns, but deserves careful scrutiny. Claims that a wood-burning stove is more harmful than 750 HGVs make for sensational headlines but lack nuance.
Examining the data closely reveals that it does not account for small particle emissions from HGV brake and engine wear. In reality, just one Euro 6 HGV, let alone 750, produces 13 times more PM2.5 emissions than an Ecodesign wood-burning stove over a week's real-world use. Moreover, wood smoke emissions rise safely through chimneys, dispersing higher above ground, whereas HGV emissions occur closer to head height.
The Stove Industry Alliance (SIA) has criticised these claims, emphasizing the simplistic calculations and the absence of peer-reviewed independent evaluation.
Not All Wood Burning Is Equal
It's essential to differentiate modern efficient stoves from other forms of domestic wood-burning, including open fires and outdoor bonfires, which are more polluting. High-quality ClearSkies rated stoves, when installed, serviced, and fuelled correctly, can reduce emissions by up to 90% compared to open fires and up to 80% compared to old stoves.
Sourcing logs from well-managed woodlands can be sustainable, benefiting both forests and wildlife. Proper forestry practices are crucial for the future of our woodlands.
Government data from 2020 revealed that only 1-2% of PM2.5 emissions could be attributed to modern Ecodesign compliant wood-burning stoves. Chief Medical Advisor Chris Whitty acknowledges the variability in emissions based on stove design, age, maintenance, and wood moisture content.
In conclusion, to effectively reduce PM2.5 levels, a pragmatic approach would target the significant emissions from open fires and old stoves while encouraging the use of modern Ecodesign ClearSkies rated wood-burning stoves and promoting the importance of using the right fuel.