If you are not a smoker, breathing wood smoke is one of the most damaging things you can do to your health.
Wood smoke particles are mostly in the fine and ultrafine size range that are most easily inhaled and most damaging to health.
A significant and growing body of research has determined that both short-term and long-term exposure to wood smoke is harmful to health and can even kill. In Europe alone, that smoke from the residential burning of natural biomass (primarily wood) causes the premature death of approximately 60,000 people a year.
Wood smoke increases airway irritation that leads to coughing and difficulty breathing. It damages lung . It aggravates asthma and . It decreases lung function and leads to the development of chronic bronchitis and diseases such as COPD.
In 2015, an article in the Canadian Medical Association Journal suggested that an increase in cases of COPD may be due to an increased use of wood stoves. Dr. Kenneth Chapman, President of the Canadian Network for Respiratory Care and a professor of medicine at the University of Toronto was quoted: “Tiny particulates, produced from combusting wood are dangerous, especially for people with pre-existing respiratory issues. It’s the same thing that’s harmful about tobacco smoke — minus the nicotine. There are volatile gases that you don’t want to inhale and can irritate the airway and lungs.”
However, there is evidence that when the particulates come from wood smoke, rather than from other sources, the risk is even higher. A found that when particulate pollution from residential wood burning was at its highest, the risk of heart attacks in seniors rose by 19%. McGill University professor Scott Weichenthal, lead author of the study, “We noticed that the association was stronger when more of the air pollution came from wood burning. This suggests that the source of pollution matters and that all particulate air pollution is perhaps not equally harmful when it comes to cardiovascular disease.”
air pollution and death rates between Santiago, Chile (where most particulates are from traffic) and Temuco, Chile (where the majority is from wood burning), found evidence that residents of Temuco faced a higher risk of death from cardiac and respiratory causes than in Santiago, even when particulate levels in the two cities were comparable.
Temuco had much higher levels of toxic polycyclic aromatic hydrocarbons (s) and other airborne toxins. Also, the size of the particles was smaller in wood-burning Temuco. “Finer particles penetrate more deeply into the respiratory system, even entering the bloodstream and thus the cardiovascular system and other organs, which could be affected by PAHs and other airborne toxins.”
It was noted that similar results have been found in studies of other cities where wood smoke is the major source of air pollution.
Recently, researchers in Sweden a population living in an area where PM2.5 came mostly from residential wood burning. They found that those who lived in an area with a 1 µg/m3 increase in PM2.5 due to residential wood burning had a 55% higher likelihood of developing dementia compared to those who were not living in an area polluted by wood smoke. Those who had a wood stove in their home and who lived in neighborhoods where wood burning was common were 74% more likely to develop dementia over the course of the study.
Exposure to wood smoke, as well as to traffic pollution, has been shown to worsen allergic reactions. It also can lower immune function. Animal studies have demonstrated that short-term, repeated exposure to wood smoke can compromise the lungs’ ability to fight off infections.
It has been shown that patients without rheumatoid arthritis who have wood smoke-induced COPD have much higher rates of an antibody associated with rheumatoid arthritis than those who have tobacco-related COPD or healthy controls. This may suggest that wood smoke is also a risk factor for triggering autoimmune diseases.
Wood smoke has been found to produce high levels of free radicals and DNA damage, as well as to promote inflammatory and oxidative stress response gene expression in human cells. Compared to diesel exhaust particles, wood smoke particles were found to cause increased levels of DNA strand breaks in a laboratory study.
Another study similarly found that particulate matter from wood smoke “generates more DNA damage than traffic-generated (particulate matter) per unit mass in human cell lines, possibly due to the high level of polycyclic aromatic hydrocarbons” in wood smoke. According to the authors of the study, “This suggests that exposure to wood smoke particulate matter might be more hazardous than particulate matter collected from vehicle exhaust with respect to development of lung cancer.” (See below for more information on cancer and wood smoke.)
Short-term exposure to wood smoke in healthy adults has been shown to increase levels of inflammation and affect blood clotting. “Relatively low levels” of wood smoke exposure have also been shown to raise biomarkers in blood, breath and urine indicating effects on airways.
It has also been shown in a laboratory experiment that the free radicals in wood smoke remain chemically active forty times longer than those from cigarette smoke. (Free radicals play a major part in the development of chronic and degenerative illnesses such as cancer, autoimmune disorders, cataracts, rheumatoid arthritis, cardiovascular diseases and neurodegenerative diseases.)
Smoking and secondhand tobacco smoke exposure are known risk factors for cataracts and eye diseases such as age-related macular degeneration. Since tobacco smoke and wood smoke share many of the same toxic chemicals, there is reason to believe that wood smoke is also harmful to the eyes. In fact, studies from the developing world have shown an association with wood smoke exposure and cataract, and laboratory evidence has also suggested that wood smoke can promote the development of cataracts.
Wood smoke contains chemicals that are listed as known and suspected carcinogens by the International Agency for Research on Cancer (IARC), as well as other chemicals that are classified as hazardous air pollutants. (For more information on chemicals in wood smoke, please see our Toxins page).
Wood smoke is associated with the development of lung cancer (for example, see here, and here). It has also been noted that children, who absorb more of the carcinogenic polycyclic aromatic hydrocarbons (PAHs) from wood smoke than adults, due to their size and physiological differences, have a higher lifetime risk of lung cancer from inhaling wood smoke than adults.
Pollution from wood stoves and fireplaces has been found to be the in Oregon’s air. from Seattle found, as well, that pollution from wood burning is a primary airborne cancer risk. The situation is likely similar in other places where wood stove use is common.
A report in Canada found that wood smoke from residential wood heating, rather than emissions from industrial sources, was “an important source of cancer-related pollutants” and recommended that, in some regions of the country, pollution reduction efforts should focus on residential wood burning for heat in order to lower cancer risk.