The truth about ecodesign stoves
Wood smoke contains at least five chemical groups classified as known human carcinogens by the International Agency for Research on Cancer (IARC), others classified as probable or possible human carcinogens by the IARC, and at least 26 chemicals listed as hazardous air pollutants by the U.S. Environmental Protection Agency (US EPA).
Pollution from residential wood burning is estimated to cause some 60,000 deaths every year in the European Union.
The reason burning wood at home is so problematic is because emissions are largely unfiltered and occur close to the ground.
Burning wood is also a lot less clean than burning gas. A Federal Office for the Environment (FOEN) study compared domestic log burners with similarly-sized gas burners and found that the former produce:
- 1,800 times more Particulate Matter (PM2.5)
- 233 times more carbon monoxide (CO)
- 125 times more non-methane Volatile Organic Compounds (VOCs)
Although pellet burners are cleaner than log burners, they still emit 800 times more PM2.5 than a gas boiler per unit of heat generated.
And don’t for one minute believe that your eco-design log burner is clean.
A study from Denmark found that a wood stove fulfilling the strictest eco-design requirements from 2022, emitted 650 times more particles that a 2014 truck!
Even just a weak smell of smoke can indicate pollution levels 5-10 times higher than areas without such an odour. More often than not, wood burning results in 25-40 times more pollutants than background levels. If your neighbour burns wood, your garden or balcony could be subjected to more emissions than those found on the most polluted city streets during rush hour.
A study carried out in the canton of Valais (see graph) compared PM2.5 levels in three different locations, namely: Eggerberg a rural village with very little wood heating (green); Sitten a town subject to heavy traffic (blue) and Veyras a rural village with a high concentration of wood burning stoves. The graph speaks for itself! The peaks would have been even more dramatic in the case of a wood burning village or town located on the valley floor which doesn’t benefit from cleansing winds and air currents.
Domestic stoves also cause significant pollution inside the home which is especially problematic in winter when people stay mainly indoors and limit ventilation. Indoor pollution is caused by a number of factors, including particles escaping when opening the stove door; leaky seals (when the latter expand through heating); a sudden air intake through the chimney and dust burning on the stove’s surface.
A study by Aalborg University, found that internal PM pollution increased 10 – 50 times above background level depending on the type of stove, with the upper measurements equating to 8-10 times more particle pollution than that found on the most polluted street in Denmark during rush hour! Such indoor particle pollution also spreads rapidly throughout the house via open doors.
As for traditional stoves such as those found in old chalets and farmhouses, they should be avoided at all costs. A study in Slovakia found that just 3 minutes after lighting such stoves, pollution inside the house had surged 125 times above the background level, to 275,000 particles per cm3.
The reason wood smoke smells is because of non-combusted volatile organic substances mixed with particles, tar compounds and dioxins.
CONCLUSION: Wood heating systems, even if they have an Ecolabel or environmental certificate, not only endanger your health, but also that of your neighbours. This is because nobody can protect themselves from the harmful particles – not even with closed windows.
So if you smell wood smoke you are ‘smelling’ pollution and your health and the health of others is at risk – no different to cigarette smoke!
April 2025