According to the findings of a new study published in the December edition of American Journal of Epidemiology, children exposed regularly to secondhand tobacco smoke at home show increased likelihood of developing emphysema in adulthood – and, in most cases, lungs may never heal completely from early-life exposure.

Emphysema, which causes destruction of alveolar walls - the place where oxygen is exchanged with carbon dioxide, brings about a reduction in the elastic function of the lungs.

The findings of the study were based on the analysis of CT scans of 1,781 non-smoking adults, by scientists at Columbia University's Mailman School of Public Health. Almost 50 percent of the participants had been exposed to at least one regular cigarette smoker in their childhood.

Upon questioning the study-participants about their exposure to tobacco smoke in childhood and studying their CT scans, the scientists found that participants with greater tobacco smoke exposure in childhood had more emphysema-like lung changes.

As per the scientists, non-smokers who lived with two or more smokers in childhood showed an average of 20 percent of emphysema-like scan pixels; as against 18 percent for those who lived with one regular smoker; and 17 percent for those who did not live with a regular inside smoker in childhood.

Commenting on the findings, lead author Gina Lovasi said that this new research “suggests that effects of tobacco smoke on the lungs may also persist for decades.”