Passive smoking in childhood or during adolescent could lead an individual to serious risk of chronic obstructive pulmonary disease (COPD), a serious condition that makes it difficult to breathe, a study suggests.

The study, conducted by researchers from the department of public health, University of Copenhagen, and published in the New England Journal of Medicine revealed that the suboptimal progression of lung function during childhood and adolescence could further develop into COPD during older age.

It is believed that around 85 percent of active smokers suffer from COPD later on. Nonetheless, not all patients at risk of COPD actually manifested a decline in their lung function.

The researchers looked into two vital lung functions which could determine COPD: first is the rapid deterioration of the lung function and the second is the suboptimal development of lung function during childhood and adolescence, which could lead to COPD in the later years.

Furthermore, another research indicated that passive smoking could also lead to stroke, with risk factors by as much as 30 percent. In fact, secondary smokers are still at risk even if they do not have other stroke factors, such as diabetes or heart disease. Secondary smoking is actually enough to trigger stroke because it prevents the normal flow of blood to and from the brain.

The study's lead researcher, Peter Lange, of the University of Copenhagen, reminded that children are particularly at risk of smoking because it hampers the normal growth of their lungs

"If you then observe them for 20 or 30 years, you find that their risk for having COPD will be 3 or 4 times greater than if they had normal lung function as young adults," he explained in an interview with Reuters Health.

The study's emphasis to keep the lungs as healthy as possible especially at an early age requires that "every effort should be done to achieve normal growth of lung function, including nonsmoking during teenage years, treatment of asthma in childhood and reducing exposure to agents like passive smoking," Lange said.