It is known that the smoke from burning wood contains substances that are harmful to health. Even so, there is no clear scientific evidence of the effects of burning wood on public health. Better research is needed into the extent to which people actually breathe in smoke. This is the conclusion of RIVM in its review of the scientific literature into the health effects of wood smoke both indoors and outdoors.
All wood smoke contains hazardous substances
When wood is burned in stoves and fireplaces, it releases chemicals such as fine particles, carbon monoxide, various volatile organic compounds and polycyclic aromatic hydrocarbons (PAHs). Many of these are harmful to health.
Still insufficient research into exposure
Although the indications are there, there is no clear scientific evidence of the effects of burning wood on public health. The reason for this is a lack of research to date into whether people breathe in smoke (both indoors and outdoors), and if so, to what extent. This depends on such factors as the type of wood-burning stove; how often, at what times and how intensively the stove is used; and the weather conditions. Exposure to wood smoke has not yet been measured accurately enough. Most studies ask people if they remember whether and how often they have used their wood-burning stoves. The conditions (including the weather conditions) in which people use their wood-burning stoves have likewise not yet been investigated sufficiently.
RIVM believes that more research should be conducted into these matters. Only then will it be possible to make a more complete assessment of the health effects of wood smoke.
What has and has not been investigated?
Most studies that RIVM describes in this literature review are about the effects of wood smoke on the lungs and airways. A small number of studies concern other effects, such as cardiovascular disease, cancer or neurological conditions. There are also a few studies into birth weight and pregnancy outcomes. These studies show variable results, and many have limitations.
Little research has been done so far among people who do not use wood-burning stoves and people in vulnerable health. A Dutch study into the exposure to wood smoke of people who do not use wood-burning stoves (Samenwerking Houtrookonderzoek, 2022) did not yield conclusive evidence of links between wood smoke and decreased lung function or increased stress, but it did establish a clear relationship between levels of wood smoke measured in the outdoor air and reported symptoms. These symptoms concerned shortness of breath when at rest and the use of medication for respiratory symptoms.
Conclusions confirm results of earlier reviews
The results of the present literature review are comparable with those of the reviews RIVM carried out in 2011 and 2019. These reviews also showed that exposure had been measured only to a limited extent.