Whether indoor environmental smoke is harmful for preschool children's respiratory health in a society where female smoking is rare has not been determined. This study is part of a cross-sectional study (CCHH study-phase one in Shanghai) and investigated associations between parental smoking and incense-burning and respiratory symptoms among 4-6 year old children in Shanghai, China. A number of 13335 valid questionnaires (response rate: 85.3%) were analyzed. A number of 56.1% (as reported by a

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... arent) of preschool children in Shanghai are exposed to environmental tobacco smoke (ETS). A number of 40.3% of fathers and 0.9% of mothers are smokers. A number of 53.7% and 12.6% of Shanghai residents have used mosquito-repellent incense and incensation respectively. Children exposed to any parental smoking have higher prevalence of wheeze and croup than those not exposed. Current maternal smoking has a significant and positive association with wheeze (in the last 12 months, AOR, 95% CI: 1.83, 1.11-2.99). However, paternal smoking either currently or at child's birth had only weak associations with wheeze and croup. Incense-burning (mosquito-repellent incense and incensation) had significant and negative association with doctor-diagnosed asthma (AOR, 95% CI: 0.85, 0.73-0.99) and hay fever (AOR, 95% CI: 0.80, 0.70-0.93). The results indicate that maternal smoking perhaps is a stronger risk factor for children's respiratory health than paternal smoking. environmental tobacco smoke, incense, asthma, wheeze, preschool children, Shanghai