Domestic heating (mainly wood burning) currently causes more than 50% percent of Europe’s black carbon emissions. Projections indicate an increase of nearly 70% in 2030. This is why wood burning has to be addressed and discussed in public and politics. Due to stricter regulation, all modern diesel vehicles are equipped with effective particle filters removing more than 99% of particles. By this, the role of road transport as source of pollution will gradually decline within the next decades.
Comparing a stove and a modern diesel vehicle, the impact from wood burning is even more obvious: Danish measurements show that the number of ultrafine particles in smoke may be more than 230 times higher than outside the smoke column – even with optimal firing with small pieces of carefully stacked bone-dry wood in a modern eco-labelled wood stove (Nordic Swan label) connected to a brand new chimney. The exhaust of a small diesel truck with a well-working particle filter only contained about 1,000 particles per cubic meter.
Many owners of stoves do not know, that wood burning also contributes to indoor pollution. This occurs if users pile the fire up and open the door as well as if the appliances are not tight. In new tight houses, there is another problem: The chimney draught “competes” with the draught from mechanical ventilation or the kitchen hood.
The Danish Building Research Institute and DEC have conducted several studies in buildings. The worst case was found in a living room with an old wood stove: Prior to starting the fire, a background pollution level of some 1,700 particles per cm3 was measured. After three hours of burning the concentrations of ultrafine particles from wood smoke in the living room attained some 30,000 particles per cm3 corresponding to levels found at roads with heavy traffic.