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Passive smoking and the seasonal difference of severity of asthma in children
1Department of Paediatrics, British Columbia's Children's Hospital, Vancouver, Canada.
Insights
Passive smoking significantly worsens asthma in children, especially during colder months. Maternal smoking showed a clear dose-response relationship with reduced lung function in asthmatic children.
Area of Science:
- Pediatric Pulmonology
- Environmental Health
- Asthma Research
Background:
- Asthma is a common chronic respiratory disease in children.
- Passive smoking is a known environmental risk factor for respiratory illnesses.
- The impact of maternal smoking on childhood asthma severity requires further investigation, particularly concerning seasonal variations.
Purpose of the Study:
- To determine if passive smoking affects children with asthma.
- To investigate if asthma severity in children of smokers is exacerbated during the cold, wet season compared to the warm, dry season.
Main Methods:
- Studied 240 asthmatic children aged 7-17 years.
- Compared lung function tests (FEV1%, FEF25-75%, PC20 histamine) between children of smoking and non-smoking mothers.
- Analyzed data for seasonal differences (cold, wet vs. warm, dry seasons) and dose-response relationships with maternal smoking.
Main Results:
- During the cold, wet season, children of smoking mothers had significantly lower FEV1% and FEF25-75% and lower PC20 histamine compared to children of non-smoking mothers.
- A significant dose-response relationship was observed between the number of cigarettes smoked by the mother indoors and impaired lung function.
- No significant differences in lung function or correlations with maternal smoking were found during the warm, dry season.
Conclusions:
- Maternal smoking significantly aggravates childhood asthma, particularly during seasons with poor ventilation.
- Passive smoke exposure from mothers demonstrates a clear dose-response effect on pediatric asthma severity.
- Environmental control of smoke exposure is crucial for managing asthma in children.
Abstract:
To learn whether asthmatic children are affected by passive smoking, we studied 240 unselected consecutively referred asthmatic subjects, aged 7 to 17 years. To discover whether children of smokers are affected more severely during the cold, wet season, when windows are closed and children are indoors, than during the warm, dry season, when houses are well ventilated and children spend more time outdoors, we compared lung function tests recorded during the two seasons. If seen during the cold, wet season, children of smoking mothers compared with those of nonsmoking mothers had a lower FEV1% (74 vs 86, p = .00), FEF25-75 percent (56 vs 75, p = .00) and PC20 histamine (0.85 vs 1.95, p = .01). There was a highly significant correlation between the number of cigarettes the mother smoked in the house and each of these lung function test results, indicating a dose-response relationship. Those seen during the warm, dry season, by contrast, did not have lower mean spirometric test results if their mothers were smokers than if nonsmokers, and there was no correlation between the number of cigarettes the mother smoked in the house and the result of any lung function test. Our results strongly support the hypothesis that cigarette smoke from the mother aggravates her child's asthma.