Perceptions of tobacco advertising and marketing that might lead to smoking initiation among Chinese high school girls: Table 1

smoking was 87.3% in the case group with LRTI (n = 150) and 84.7% in the healthy children group (n = 150), with no significant difference (p = 0.618). However, a significant difference was found between passive smoking prevalence in groups at a urinary CCR of 60 ng/mg (76.7% and 50.7%, respectively) (p,0.001). The children with LRTI had more dense ETS exposure compared to the healthy children (OR = 4.72; 95% CI = 2.62 to 8.51). When the cut-off level of urinary CCR was accepted as 60 ng/mg creatinine, it was found that passive smoking increased LRTI in children significantly (p = 0.000). This finding indicated that the causative effect on LRTI of passive smoking was dose dependent.