Despite this being a common perception of wood-burning fireplaces, it is unfortunately misguided. Wood smoke has been found to be a significantly more potent carcinogen than cigarette smoke, with long-term exposure coming with a myriad of potential health consequences.
The main culprit of the human health risks associated with wood burning is a type of airborne pollutant known as particular matter (PM), which is made up of tiny solid particles and liquid droplets in the air. These are often grouped into two categories based on particle size; PM10 being 10 microns or less in diameter and PM2.5 is 2.5 microns or less. Whilst both have the potential to cause health problems, the smaller particle sizes can stay suspended in the air for longer and travel further, making them more hazardous.
Children are particularly vulnerable to these effects; those living in homes with active wood burners suffer from higher rates of asthma, bronchitis, and compromised lung function. These same trends are even seen in children simply living in areas where wood burning is common. Indeed, wood and coal-burning stoves are estimated to account for 38% of PM air pollution in the UK, according to the government’s ‘Clean Air Strategy 2019’, which the government aims to reduce to 30% by 2030.
Whilst wood burning can increase the outdoor concentrations of particulate matter, the major health concerns relate to indoor air quality. Research conducted in 2020 which was published in the journal Atmosphere found that during the time a wood burner was lit, the level of particulate matter in homes was three times higher than when it was not in use. Concentrations rose to as high as 195 micrograms per cubic metre (µg/m3). To put the severity of this value into perspective, the legal limit for PM10 in the UK is currently set at 40 µg/m3 and 20 µg/m3 for PM2.5, with the WHO’s recommended limit lower still, at 5 µg/m3.
To help address this issue, the government introduced new regulations which took effect in January 2022, essentially banning the sale of all newly manufactured wood-burning stoves and fireplaces which do not meet the stricter new guidelines known ‘Ecodesign’. These stoves are independently tested by an approved laboratory to meet new requirements on pollutant emissions. For those living in smoke control areas, the use of a wood burner that is not listed as a Defra-exempt appliance could result in a fine of up to £1,000.
There are certain actions that can be taken by those using wood burners to reduce the risks; ensuring that wet or unseasoned logs are not used, regular cleaning and maintenance of the stove, having good ventilation, and using a high efficiency stove are all steps that can help to reduce emissions and therefore harms associated with burning wood.
The Air Quality and Climate team at Temple may also play a role in helping to identify and reduce the harms associated with wood burning. The Temple team has the expertise and technical apparatus which would enable them to undertake real-time monitoring of particulate matter in homes with wood stoves and could therefore advise on the implication of the indoor air quality arising from wood burning in these households. With these new regulations in place and increasing awareness surrounding this issue, the harms associated with wood burning are expected to fall in the coming years.