MedWire News: Childhood exposure to environmental tobacco smoke (ETS) in the home is significantly associated with an increased risk for wheeze and asthma, research confirms.
Previous studies have shown that maternal smoking during pregnancy increases the risk for wheeze, asthma, and other health problems in children, explain Yungling Leo Lee (National Taiwan University, Taipei, Taiwan) and colleagues.
But they add that evidence for effects of childhood ETS exposure on respiratory outcomes is inconsistent.
To investigate further, the team studied 5019 children, aged 12–14 years, from 14 Taiwanese communities who participated in the Taiwan Children Health Study.
Parental questionnaires were used to assess the children’s asthma status, age at asthma diagnosis, and history of respiratory symptoms. Parents also supplied information on their smoking habits, including maternal smoking during pregnancy, and their children’s exposure to ETS at home.
The researchers found that 11.6% of children had suffered from wheeze at some point in their lives, and 7.5% had doctor-diagnosed asthma. Around two-thirds of children with asthma were diagnosed before the age of 5 years.
Overall, 3.9% of children were exposed to maternal smoking in utero, 49.0% were exposed to household ETS at any time during their lives, and 44.9% were currently exposed to household ETS. The prevalence of paternal and maternal smoking was 36.0% and 3.4%, respectively.
After accounting for factors such as age, gender, parental education, and parental history of asthma and atopy, the researchers found that in utero exposure to maternal smoking was associated with a 1.67-fold increased risk for asthma diagnosed before 5 years of age, and a 1.49-fold increased risk for the disease after this age.
Although exposure to maternal or paternal smoking alone was not independently associated with respiratory outcomes, exposure to ETS from both parents was associated with a 2.01-fold increased risk for asthma before the age of 5 years, but was not significantly associated with childhood asthma after this age.
However, it was also associated with a 4.30-fold increased risk for serious asthma (emergency room visit or hospitalization) at any age.
Exposure to ETS from both parents was also associated with an increased risk for ever wheeze (odds ratio [OR]=1.81), current wheeze (OR=2.74), bronchitis (OR=1.97), and chronic phlegm without cold (OR=2.65), after adjustment.
Lee and team conclude in the journal Respiratory Research: “Our results showed that prenatal and current household ETS exposure in Taiwan had significant adverse effects on respiratory health in children.”
They add: “Eliminating household ETS exposure may offer the most promising opportunity for reducing morbidity, because this risk factor is potentially modifiable.
“Public health policy for reducing the burden of respiratory symptoms may require a stronger focus on smoking cessation in the home, where children could gain significant health benefits.”
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