Children are among the most vulnerable to the harmful effects of air pollution. Children breathe faster and inhale more pollutants in proportion to their body weight than do adults. Their immune systems and organs are still developing.
Particle pollution has been shown to affect lung function and lung development. Eighty percent of the lungs’ alveoli are formed after birth, and children’s lungs continue to develop through adolescence.
During infancy, the developing lung is highly susceptible to damage from environmental pollutants, including those from wood smoke.
Effects During Gestation and Birth
Numerous negative effects on fetal development and birth outcomes have been linked to air pollution exposure.
Low Birth Weight and Reduced Fetal Growth
Exposure to PM2.5 is linked to lower birth weights and smaller birth size.
A study in Sweden found that the clearest association with low birth weight and particle pollution was when the source of the PM2.5 was residential wood heating.
Fine particle pollution has been strongly associated with reductions in fetal head growth and size, even at PM2.5 levels that are below current regulatory “safe” threshold values. The documented effects are similar to those that result from smoking during pregnancy.
Exposure to particle pollution has been associated with increased risk of premature birth, even when, again, PM2.5 levels are relatively low.
Increased exposure to PM2.5 during pregnancy has also been linked with an increased risk of miscarriages and stillbirths.
Toxins Reach Placental Tissue
Polycyclic aromatic hydrocarbons (PAHs), which are in wood smoke (please see our Toxins page), have been shown to reach placental tissue in several studies. Once in the placenta, they may impair fetal nourishment and growth.
Pollution Particles Are Embedded in Fetal Organs
In 2022, research published in Lancet Planetary Health found that black carbon air pollution particles inhaled by pregnant women cross the placenta and become embedded in the lungs, liver and brain, as well as the placenta, of the fetus during gestation.
The researchers described these findings as “especially concerning because this window of exposure is key to organ development,” and happens at a time when “susceptibility for many diseases later in life is programmed.”
The research provided evidence of how the developmental harms that are linked to air pollution are caused. (Residential wood burning is a large source of black carbon.)
High Blood Pressure Disorders in Pregnancy
A study in Monroe County, New York, linked ambient wintertime air pollution specifically from wood burning (but not from other sources) with an increased risk of the mother developing a hypertensive disorder during late pregnancy.
Increased Infant Mortality
An increase in ambient PM2.5 has been associated with an increase in newborn deaths, especially from respiratory-related causes.
Researchers in Europe, for example, found that infant mortality rates rise on days with increased particle pollution. They also found no evidence of a threshold level below which risk is not increased.
Air Pollution Before Conception
There is also evidence that a mother’s air pollution exposure before conception can affect later development of the fetus.
For example, a mother’s exposure to increased levels of PM2.5 in the month before becoming pregnant has been linked to increased risk of birth defects.
There is evidence that exposure of a mother to PM2.5 before pregnancy may affect her child’s cardiac function in later life.
Effects on Fertility and Fertility Treatment
Air pollution exposure has been linked to reduced fertility. There is also evidence that women undergoing fertility treatment are less likely to have a successful pregnancy when air pollution levels rise.
In a study of air pollution and IVF at the Bordeaux University Hospital in France, it was found that the likelihood of a successful pregnancy was reduced by 25% after a biomass boiler was installed 100 meters from the fertility clinic. “The fine particles emitted by the biomass burning process may have adverse effects on gametes and embryos,” the researchers noted.
Brain and Neurological Development
Evidence suggests that exposure to fine particle pollution during pregnancy is linked to autism. A 2023 study from Sweden found an association with a mother’s exposure during pregnancy to pollution from residential wood burning specifically, as well as from other sources, and autism.
PAHs Linked to Mood and Attention Problems
There is growing evidence that fine particle pollution, especially with increased levels of PAHs, can lead to impaired neuropsychological development and a lifelong lowered IQ. As we have noted elsewhere, wood smoke pollution is particularly rich in PAHs.
Prenatal exposure to higher levels of PAHs has also been linked to more mood and attention problems in children when they reach school age.
Risk Factor for Later Neurological Disease
Researchers who study how air pollution affects the brains of children and young adults have concluded that exposure to air pollution early in life should be considered a risk factor for later Alzheimer’s and Parkinson’s diseases.
Lung Development and Respiratory Health
Research has shown that infants exposed to more ultrafine particulate matter (the size range most prevalent in wood smoke) developed genetic defects that caused the production of proteins associated with COPD and steroid-resistant asthma in adults. These genetic defects were linked to structural changes in the lung, airflow limitations, and permanent changes in immune responses.
Wood smoke pollution has been linked to increased risk of bronchiolitis, a respiratory disorder that is a leading cause of hospitalization in infants, as well as to rates of hospitalization for childhood pneumonia and bronchitis. Studies have also shown that children living in homes with wood stoves are more likely to have severe respiratory symptoms (PDF).
For children who already have serious illnesses, wood smoke can be particularly harmful. For example, a study found that primary and secondary aerosol emissions from a newer model wood stove were cytotoxic to, and caused inflammation in, bronchial epithelial cells from both healthy donors and from those with cystic fibrosis, but the emissions were even more cytotoxic to the cells from donors with cystic fibrosis.
Increased Asthma Attacks and Hospital Visits
Children who are exposed to higher levels of particulate pollution, including from wood smoke, are more likely to develop asthma by age 5.
Researchers found that asthmatic children living in neighborhoods with more wood smoke were more likely to have significant decreases in lung function. The study’s authors noted, “wood smoke resembles environmental tobacco smoke, for which numerous studies have shown deleterious effects on the respiratory health of children.”
Several studies in Seattle, where wood burning is a primary source of fine particles, have shown a strong correlation between particulate levels and emergency room visits and hospitalizations for asthma.
A study in New Zealand found that each additional wood stove per hectare increased by 7% the number of non-accident-related hospital emergency visits for children under 3. The study’s authors estimated that one less wood stove per hectare could prevent 9,000 emergency department visits each year for young children in New Zealand.
More Ear Infections
Fine particle pollution exposure is linked to increased ear infections in young children, as is pollution specifically from residential wood burning.
Links to Cancer Risk
A study found an association between use of a wood stove in the home and childhood brain tumors. Another study found evidence that use of a wood stove in the year before or during pregnancy may increase the chance of a child developing acute lymphoblastic leukemia.
DNA Damage From PAHs
Researchers have suggested that children have a higher lifetime risk of lung cancer from inhaling wood smoke than adults. Due to their size and physiological differences, children absorb more of the carcinogenic polycyclic aromatic hydrocarbons (PAHs) that are in wood smoke.
Developing fetuses are particularly susceptible to developing DNA damage from PAHs compared to adults.
As a society, we no longer think it is acceptable to force children to breathe secondhand cigarette smoke. It’s time to extend this attitude to wood smoke.