Defra data cuts wood burner emissions but action is still needed

While home use of solid fuel is a leading source of particle pollution, CIEH points out the complexity of the issue – kiln dried wood is less polluting than wet wood, and oil and gas are unsustainable

New data from the Department for Environment, Food and Rural Affairs (Defra) cuts the estimated proportion of small particle pollution produced by wood burners from 38% to 17%, but the total still outweighs that produced by the UK’s road traffic, which is responsible for 13% of particle pollution.

Domestic wood burning is described as a ‘major source’ of particulate matter (PM) emissions, accounting for 15% and 25% of PM10 and PM2.5, respectively in 2020.

The UK government is focused on reducing the amount of PM10 (less than 10 micrometres in diameter) and PM2.5 (less than 2.5 micrometres) due to their ability to penetrate the lungs, blood streams and brain, causing health problems that include heart attacks and respiratory disease.

Defra notes that emissions of PM2.5 from domestic wood burning increased by 35% between 2010 and 2020 and it states that “most emissions from this source come from burning wood in closed stoves and open fires.”

Air-pollution scientist, Dr Gary Fuller of Imperial College London said: “Home use of solid fuel is one of the top two sources of particle pollution in the UK, coming from just 8% of UK homes. My in-box is filled with people who are concerned about the wood smoke that is filling the bedroom of their asthmatic child or ill elderly relative.”

Matthew Clark, Programme Manager for Air Quality at Hertfordshire County Council, said that that while there could be a place for solid fuel burning in rural areas not well served by other means of fuel, that wasn’t the case in urban areas. “Burning solid fuel is much more polluting than any other prevalent means of heating a domestic property.” He added that PM2.5 exposure is “correlated to the chronic health conditions of our time” and that “it seems socially as well as environmentally essential to move away from this heat source.”

“While there is no doubt that fuels used for central heating, namely oil and gas, are cleaner [than wet wood] they are also unsustainable. Wood on the other hand is sustainable.”

However, as Gary McFarlane, CIEH Northern Ireland Director makes clear, there are other aspects to consider. He said: “As with most complex issues, there are no easy answers. Wood burning can be polluting, as can the burning of other solid fuels. My understanding is that the level of pollution from burning wood is significantly influenced by the type of wood fuel being used, in particular its moisture content. Kiln dried wood is significantly less polluting than so-called ‘wet’ wood.

“While there are controls on wet wood sales, that does not prevent its use. And while there is no doubt that other fuels used for central heating, namely oil and gas, are cleaner, they are also unsustainable. Wood, on the other hand, is sustainable. We cannot continue to burn those fuels either if we are to avert climate catastrophe.

“This latest report focuses on the fluctuating pattern since 2000. The massive gains made through clean air legislation in the late 1970s and early 1980s are largely still being maintained. As with many of these complex issues, things need to be considered in their totality. Yes, we have PM2.5 issues. We also have a climate emergency. Unsustainable fossil fuel  burning whether in central heating or in vehicle use must be phased out. There are no easy answers and there needs to be a much more integrated approach to meeting these challenges.”

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