Parents, think twice before lighting up in front of your children: you could be setting them up for long-term respiratory illness, according to a study presented last Sunday at the American Thoracic Society International Conference in San Francisco. Earlier studies had established a link between parental smoking and childhood respiratory illness, but in this study, University of Arizona researchers looked at whether these effects persisted into adulthood. 'This study shows that exposure to parental smoking increases the risk of persistence of respiratory symptoms from childhood into adulthood independent of personal smoking,' says Juliana Pugmire, one of the researchers. 'Persistent respiratory illness in childhood and young adulthood could indicate an increased risk of chronic respiratory illness and lung function deficits in later life.' The researchers drew data from the Tucson Epidemiological Study of Airway Obstructive Disease (TESAOD), a population-based, prospective study initiated in 1972 that enrolled 3,805 individuals from 1,655 households in the Tucson area in an effort to assess prevalence rates and risk factors of respiratory and other chronic diseases. Participants completed questionnaires issued every two years until 1996. For this study, the researchers used data from 371 individuals who were enrolled in the TESAOD as children under 15 years of age. The researchers looked at the reported prevalence of active asthma, wheeze, cough and chronic cough, which was defined as a persistent cough that lasted for three straight months. They found that 52.3 per cent of the children were exposed to environmental tobacco smoke (ETS) before age 15. After adjusting for sex, age, years of follow-up and personal smoking status, it was found that ETS exposure in childhood was significantly associated with several persistent respiratory symptoms. 'Persistent wheezing from childhood into adult life has been shown to be associated with lung function deficits,' notes Pugmire. 'Chronic bronchitis [defined as chronic cough and phlegm] is a significant risk factor for chronic obstructive pulmonary disease [COPD] development later in life. Therefore, 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.' A study by Hong Kong Polytechnic University researchers published in 2010 in the Journal of Advanced Nursing looked at students aged 13-15 years old in two schools and found that 44.7 per cent of students had parents who smoked. Of these, 13.2 per cent had tried smoking, compared to 3.8 per cent in those with non-smoking parents. Pugmire says future studies will be needed to examine the potential synergistic effects of personal smoking and exposure to parental smoking on risk of COPD morbidity and mortality in middle to late adult life.