The relative importance of socio-economic status, parental smoking and air pollution (SO2) on asthma symptoms, spirometry and bronchodilator response in 11-year-old children.

The aim of this study was to evaluate the relative contribution of several risk factors to the prevalence of allergic respiratory symptoms, and the positivity of the bronchodilator test with fenoterol, and to establish the relative importance of these factors on the variability of FVC, FEV1, PEF, MEF25, MEF50 and MEF75. A total of 340 11-year-old children attending school in polluted and non-polluted areas of the city of Cartagena, Spain, were studied. The polluted area had had an annual mean of 75 microg/m3 of SO2 over the last 10 years and the non-polluted area had < 20 microg/m3 during this period. A questionnaire about allergic respiratory symptoms was completed by the parents. Specific questions about parental smoking habits and socio-economic level were included. Each child's performance in spirometry before and after administration of 0.2 mg of inhaled fenoterol was evaluated. The only significant predictive variables in the logistic regression (for suffering any symptom or a positive bronchodilator response) were male sex for nasal symptoms (RR 1.37; p = 0.04) and housing near heavy traffic for eye symptoms (RR 1.45; p = 0.01). Living in the polluted area reduced the risk of a positive bronchodilator response (RR 0.61; p = 0.004). Maternal smoking, even though not statistically significant, tended to increased the risk of suffering any symptom (RR 1.26; p = 0.07) or of having a positive bronchodilator response (RR 1.23; p = 0.1). None of the risk factors studied was of significant importance in explaining the variability of spirometry results. Although none of the risk factors were specifically determinant to the symptom questions, bronchodilator test or spirometric measurements, having a mother who smokes seems more important than living in a polluted area if statistically non-significant trends are considered.