A University of Arizona team which analysed the results of 24-year-long study found that non-smokers who were exposed to passive smoking during their childhood had a higher risk of developing chronic chest infections.
The study assesses the prevalence rates and risk factors of respiratory and other chronic diseases of the participants who had to complete questionnaires in every two years from 1972 until 1996.
The researchers found that 52.3 per cent of the children had been exposed to tobacco smoke between birth and 15 years old. After adjusting for sex, age and personal smoking status, the researchers found that this exposure was significantly associated with several persistent respiratory symptoms.
"We examined asthma as well as other respiratory symptoms and found that exposure to parental smoking had the strongest association with cough and chronic cough that persisted into adult life," study author Juliana Pugmire was quoted as saying by the Daily Mail.
"Exposure to parental smoking also had effects, although weaker, on persistent wheezing and asthma in adulthood."
While researchers have warned of the potential health risks of second-hand smoke for 30 years, there have been few studies into the long-term effects on children.
"Earlier studies established a link between parental smoking and childhood respiratory illness, but in this study, we sought to demonstrate whether these effects persisted into adulthood," Pugmire said.
Noting that wheezing and a chronic cough were early risk factors of far more serious lung conditions, Dr Pugmire said: "Persistent wheezing from childhood into adult life has been shown to be associated with lung function deficits.
"Chronic bronchitis is a significant risk factor for chronic obstructive pulmonary disease (COPD) development later in life. Thus, the persistence of symptoms like chronic cough and wheeze into young adulthood may indicate a susceptibility to lung function deficits and chronic respiratory illness with age," she said.
The study was to be presented at the ATS International Conference 2012 in San Francisco.
