A study into particulate matter emissions from domestic wood burning has seen no significant upward trend the concentration of PM 2.5 & 10 in urban areas, despite a reported rise in the number of households burning wood.
Research into emissions from domestic wood burning was carried out by researchers at Kingâ€™s College Londonâ€™s Environmental Research Group, led by Gary Fuller, a senior lecturer in air quality measurement.
Dr Fuller presented the findings of his study at KCLâ€™s London Air Quality Network (LAQN) Conference last week (13 July).
He explained that the study had been carried out as information published by the Department for Energy and Climate Change (DECC) last year had suggested that â€œdomestic wood burning in the UK has been systematically underestimated by about a factor of three.â€
The DECC Domestic Wood Use Study, published in March 2016, suggested that 52% of wood burning appliances are stoves and 40% are open fires, with most wood users located in the South East of England.
As part of the Kingâ€™s College study emissions were monitored using an aethalometer, which measures how much light is absorbed by particles on a filter.
Dr Fuller noted that the findings, which were taken in towns and cities including Norwich, London and Birmingham, showed that there was a peak in wood burning on weekday evenings and weekends. However, the study also drew some unexpected conclusions.
Dr Fuller said: â€œOne of the most intriguing things of the project, what we expected to see from the popularity of wood burning â€“ weâ€™d expected that there would be lots of evidence that wood burning PM is going up and that this is a worsening problem. But surprisingly to us that is not what we found.
â€œWe spent a lot of time trying to do trends to see if we were getting a robust and consistent result. If we de-seasonalise it running along the trends graph we get numbers that are pretty flat.â€
Dr Fuller claimed that the trends were â€˜puzzlingâ€™ but he suggested that they could be ascribed to consumers using more efficient wood burning stoves than older models.
Pointing to data from the Stove Industry Alliance, which suggests that as many as one million stoves have been sold in the UK since 2010, he said: â€œYouâ€™d see this and think that wood burning must be going up â€“ so how do we explain this flat tendency?
â€œIt is possible that we missed all of the excitement, if we had started the measurement programme back at the start of the century it could be that we missed the rise of wood burning and that those who are into it perhaps started with an old stove or a fire place actually replacing this with more modern stoves.
â€œWe are probably seeing an increase in the amount of wood burned but a move to more efficient stoves.â€
Despite not showing an anticipated increasing trend in particulate matter emissions, Dr Fuller noted that the contribution of wood burning to PM in urban areas is â€˜very significant indeedâ€™ and is potentially amounting to around 23% and 31% of emissions during peak times.