Growing up in the house of a smoker sets children on a number of lifelong paths. Chief among them is the damage done to a child’s lungs. But that’s not the only consequence, and a new international study published in the European Heart Journal adds one more to the list: Secondhand smoke leads to thicker arteries in kids.

It’s an easy leap to make, that secondhand smoke primarily causes lung damage. That is where the smoke travels first, after all. In children whose bodies and brains are still developing, the 200+ carcinogens found in cigarette smoke can also lead to an increase in ear infections, coughs and colds (and an inability to fight those illnesses), tooth decay, and pneumonia. With greater exposure, they’re also more likely to lead to lung cancer, heart disease, and cataracts. And now that researchers have thrown thicker arteries into the mix, kids find themselves at risk for heart attack and hypertension.

Worse, unlike the changeable nature of smokers’ physical consequences, in children’s formative years much of the damage may stick with them forever. "Exposure to passive smoke in childhood causes direct and irreversible damage to the structure of the arteries,” lead researcher from the University of Tasmania, Seana Gall, told Reuters. By the time kids reach adulthood, the team found, secondhand smoke has added an average of 3.3 years to their blood vessels.

Arteries mostly carry oxygenated blood away from the heart to the body’s various extremities, providing the cells with oxygen so they can perform their necessary vital functions. When a person’s arterial walls thicken, the blood has a limited space it can travel through, forcing the heart to work harder to maintain the same flow. This resulting force is what ultimately determines a person’s blood pressure. Obesity is a major cause of high blood pressure, as the fat that builds along the artery walls ends up clogging the blood vessels. But now researchers say secondhand smoke reaches the same result.

Australian and Finnish scientists tracked nearly 4,000 subjects from childhood through adulthood. The team asked children about their parents smoking habits, in addition to taking an ultrasound of each (now adult) child’s arterial walls. They checked for wall thickness in the innermost two layers, known as carotid intima-media thickness, or IMT. Ultimately, they found children whose two parents both smoked had greater carotid IMT by 0.015 millimeters.

Where Smoking Should Go

Gall called this a “modest” increase, though still an increase to give concern. Parents and policymakers alike should accept the real and lasting effects secondhand smoke produces (to say nothing of third-hand smoke). No federal ban exists in the U.S., but many local and state governments have made the decision to ban smoking in all public places, most notably restaurants, airports, hospitals, and workplaces. Some have even jumped on-board with smoking bans in private cars, provided there is a child under a certain age present. Britain will enact their ban next year, and states like California, Alaska, Louisiana, and Oregon have all set minimum ages for when parents can smoke — Louisiana on the low end at 13, and California and Oregon pushed all the way to 18.

Critics have argued that such bans unnecessarily infringe upon their right to privacy. But their voices may be drowned out by the 82 percent of Americans who support no smoking in vehicles with children younger than 13 in the car, and the 75 percent who support no smoking in homes where children have asthma, according to a 2013 University of Michigan poll. Vehicular bans are of course more enforceable than household bans, but the sentiment remains the same. Smoking is becoming decidedly less cool to the American public, and the pool of smokers begrudgingly complying with tightening laws is shrinking. Whether it’s because of cost or social stigma, smoking is simply too inconvenient for many. The drop from a 42.4 percent smoking rate in 1965 to 18 percent in 2011 reflects this.

"Legislation can reduce passive smoke exposure, with restriction of smoking in public places reducing hospitalizations for cardiovascular and respiratory disease," the researchers wrote, highlighting the positive effect a smoking ban in cars would have. “There must be continued efforts to reduce smoking among adults to protect young people and to reduce the burden of cardiovascular disease across the population.”

Source: Huynh Q, Magnussen C, Juonala M, et al. Exposure to parental smoking in childhood or adolescence is associated with increased carotid intima-media thickness in young adults: evidence from the Cardiovascular Risk in Young Finns study and the Childhood Determinants of Adult Health Study. European Heart Journal. 2014.