Table 1

Study design and number of participants

City	Adult smoker		Adult nonsmoker		Youth (13–17 years)		Total
City	Male	Female	Male	Female	Male	Female	Total
Beijing	55	40	39	47	51	45	277
Kunming	50	50	46	50	50	50	296
Shanghai	51	52	47	50	50	50	300
Yinchuan	50	48	48	50	50	50	296
Totals	206	190	180	197	201	195	1169