Burning and heating with wood produces the most harmful particulate matter
Doctors previously assumed that health problems caused by particulate matter could be avoided by reducing the concentration of particles in the air.
However, in 2022, researchers at the Paul Scherrer Institute (PSI) came to the conclusion that the effects of particulate matter do not primarily depend on the number of particles, but rather on the source of the pollution, their toxicity and the way they enter the body. It is striking that although the fine dust particles vary from place to place, the most important source of pollution is strikingly similar: Namely, heating with solid fuels.
When logs, wood pellets or coal are used for heating, a lot of particulate matter is released that is harmful to the health of the local population.
In contrast to power plants, for which there are strict regulations and filter systems, emissions from residential heating systems are not subject to sufficiently strict regulations in most European countries, including Switzerland.
“Wood is a natural material. This is probably why many people are not aware of how harmful burning wood is to health,” says Gang Chen, aerosol researcher at the Paul Scherrer Institute.
The researchers hope that their work will raise public awareness of the effects of building heating systems on air quality. Paul Scherrer Institut (PSI)
The Federal Office for the Environment FOEN (Federal Office for the Environment) explains that local space heaters must comply with European ecodesign emission standards when they are placed on the market.
However, a wood-burning stove that meets the strictest ecodesign requirements emits 650 times more particles than a normal truck. Study
To reduce pollution from new wood stoves to an acceptable level, the filters would need to have an efficiency of 99.9% (to achieve the same particulate pollution as a newer truck per GJ of energy), but cleaning to this level can only be achieved with a flue gas condensation system combined with bag filters or wall-flow filters, which are not yet available on the market.
In the canton of Berne, most district heating systems run exclusively on pellets. But even large waste incineration plants often need an additional third of wood to increase the temperature.
Even if the filters installed in large incineration plants filter out 99% of the fine dust, the air is still polluted by the large quantities that are burned, which is harmful to health.
Environmental hygienist Manfred Neuberger from the Medical University of Vienna also says that environmental certificates are issued to incinerators even though they do not meet the limit values. The reason for this is the strong timber industry lobby.
During energy transition, politicians should focus on promoting geothermal heat pumps, wind power, solar energy and building insulation rather than wood combustion.