Children whose fathers were exposed to secondhand smoke during childhood face a significantly higher risk of developing poor lung health as adults, according to new Australian research published in the journal Thorax.
The study is among the first to suggest that the damaging effects of tobacco smoke may extend beyond those directly exposed, potentially affecting future generations. Scientists say the findings highlight the intergenerational impact of smoking and the importance of protecting children from passive smoke.
“These findings suggest that smoking may adversely affect lung function not only in smokers but also in their children and grandchildren,” the researchers wrote.
The study tracked 890 fathers and their children, who were born in the early 1960s, over more than five decades. Researchers examined whether the fathers had been regularly exposed to secondhand smoke before puberty — defined as having at least one parent who smoked six or more days a week — and then assessed the lung health of their children at age 53.
Results showed that children of fathers exposed to secondhand smoke during childhood were 56 percent more likely to suffer from poor lung function, measured by forced expiratory volume in one second (FEV1), a key marker of respiratory health. They were also more likely to show signs of rapid decline in lung function, even if they had not yet developed chronic obstructive pulmonary disease (COPD), a leading global cause of death.
“Impaired lung function may begin long before respiratory illnesses become clinically apparent,” said Professor Shyamali Dharmage, of the University of Melbourne’s Allergy and Lung Health Unit, who co-authored the study.
The link remained strong even after accounting for other potential factors, including socioeconomic background and family history of asthma. The association was particularly pronounced among children who themselves were also exposed to secondhand smoke while growing up.
The study found that 69 percent of fathers and 57 percent of their children had been exposed to secondhand smoke in childhood. Nearly half of the children also reported smoking at some point in their lives. However, researchers said the children’s own exposure explained only about 10 percent of the connection between poor lung health and their fathers’ early exposure, suggesting a deeper intergenerational effect.
Scientists believe the mechanism may be biological. Boys exposed to harmful chemicals in cigarette smoke before puberty may undergo changes in the genetic expression of sperm cells, which could then affect the respiratory health of their offspring.
Although the study was observational and cannot definitively prove causation, its authors stressed the importance of preventing children’s exposure to smoke.
“Protecting children from passive smoke could benefit not only their own respiratory health but also that of their offspring,” Dharmage said.
The researchers urged fathers to break the cycle by avoiding smoking around their children, warning that the consequences of exposure may ripple across generations.
