Although using a renewable energy source, wood heating contributes significantly to air pollution episodes and to the ambient level of fine particles suspended in the outdoor air. According to a 2015 study (source AIRPARIF) in the Paris region, domestic wood heating contributes to 28% of primary PM10 and 42% of PM2.5 (< 2,5 microns). Open fireplaces and closed fireplaces built before 2002 account for 75% of the particles emitted.
Wood combustion emits pollutants that vary according to the efficiency (output) of the appliance and the moisture content of the wood. Generally these are carbon monoxide (CO), water, nitrogen oxide (NOx), NMVOCs, soot, tars, coal, volatile organic compounds (VOCs), polycyclic aromatic hydrocarbons (PAHs), H², SO², etc.
According to the health protection agencies (regional health observatory – ORS), wood heating with fuel loading directly into the room to be heated (not to be confused with a wood boiler in your basement) is a major source of pollution in residential housing.
If the particles resulting from the (imperfect) combustion of wood are inhaled (open fire, smoke that escapes when starting or (re)loading the wood, leaks linked to a lack of airtightness, pollutants following the elimination of ashes, wood combustion of neighbours by the outside air that comes inside, etc.), the health risks are real. When they penetrate the respiratory system they will promote asthma, coughing, respiratory allergies. Never burn damp wood, which will give off a lot of water vapour, and therefore moisture and mould. Globally (without distinction by pollutant) the deleterious effects are (according to the regional observatory of health of Ile de France): irritation, inflammation, oxidative stress, carcinogenic, neurotoxic, mutagenic, impacts on the cardiovascular system.