Indoor and outdoor risk factors related to allergic rhinitis and/or asthma in children and adolescents

selected half of this study population for cotinine, which was measured by ELISA. High ETS exposure was defined as urinary cotinine ≥30ng/mg creatinine. Results: Nineteen nurseries and kindergartens were recruited from all four geographical regions of Hong Kong. 1402 (73.4%) of 1909 consented children, with mean(SD) age of 4.8(0.9) years, successfully performed incentive spirometry. Current maternal smoking was reported in 190 (10.0%) of the consented children. Cotinine was undetectable only in 37.6% of 893 urine samples, whereas 95 (10.6%) of them had high urinary cotinine level. High ETS exposure was associated with reduced forced expiratory volume in 0.5-second (FEV0.5), FEV0.75, forced vital capacity, forced expiratory flow between 25% and 75% of expiration (FEF25–75) and peak expiratory flow (PEF). Their respective mean values were: 0.70 L vs 0.75 L, P < 0.05; 0.78 L vs 0.89 L, P < 0.005; 0.97 L vs 1.07 L, P < 0.05; 1.24 L/s vs 1.48 L/s, P < 0.005; and 1.96 L/s vs 2.11 L/s, P < 0.05. Urinary cotinine-to-creatinine ratio also showed consistent inverse correlations with forced expiratory parameters (FEV0.5: r = −0.126, P =0.009; FEV0.75: r = −0.095, P =0.054; PEF: r = −0.122, P =0.012). Conclusion: High urinary cotinine as an indicator of ETS exposure is a strong risk factor for diminished forced expiratory parameters measured by incentive spirometry in Hong Kong Chinese preschool children. Funding: Health and Health Services Research Fund (06070261), Hong Kong SAR