New U.S. research has found that exposing children to secondhand smoke can increase their risk of death from chronic obstructive pulmonary disease (COPD) death in adulthood, with adults exposed to secondhand smoke also showing a higher risk of death from several other conditions.

The study by researchers at the American Cancer Society investigated the associations between childhood and adult secondhand smoke exposure (smoke exhaled by smokers and from the burning tip of the cigarette) and ischemic heart disease, stroke, and chronic obstructive pulmonary disease, and death from all causes.

The researchers gathered data from among 70,900 men and women who had never smoked. The majority of participants were between the ages 50 to 74 at the beginning of the study.

They were asked to answer questions about their exposure to secondhand smoke, both during childhood and as adults, and they were then followed for a period of 22 years.

The results showed that participants who reported living with a daily smoker throughout their childhood had a 31 percent higher risk of mortality from chronic obstructive pulmonary disease compared to those who did not live with a smoker, which the researchers calculated corresponds to around 7 additional deaths per year per 100,000 never-smoking study participants.

Although the study measured deaths from COPD, the researchers also added that the increase found in fatal COPD implies that living with a smoker during childhood could also increase risk of non-fatal COPD.

In addition, more than ten hours a week of exposure to secondhand smoke exposure as an adult was also associated with a 42 percent higher risk of death from COPD, as well as a 9 percent higher risk of all-cause mortality, a 27 percent higher risk of death from ischemic heart disease, and a 23 percent higher risk of death from stroke.

The researchers added that the link between adult exposure to secondhand smoke and an increased risk of death is consistent with findings from previous studies. Though active smoking is a more important factor in increased mortality, secondhand smoke exposure is still a moderate risk factor comparable with other secondary risk factors.

"This is the first study to identify an association between childhood exposure to secondhand smoke and death from chronic obstructive pulmonary disease in middle age and beyond," said lead researcher W. Ryan Diver, MSPH. "The results also suggest that adult secondhand smoke exposure increases the risk of chronic obstructive pulmonary disease death. Overall, our findings provide further evidence for reducing secondhand smoke exposure throughout life."

The results were published online in the American Journal of Preventative Medicine