Decrease in the prevalence of smoking among Japanese adolescents and its possible causes: periodic nationwide cross-sectional surveys

Table 4 Association between variables of students’ smoking and school smoking regulation

Sex	High school	School policy	Number of schools	Lifetime smoking		Current smoking		Daily smoking		Number of students
Sex	High school	School policy	Number of schools	OR	CI	OR	CI	OR	CI	Number of students
Male	Junior	Insufficient separation of smoking	23	1.0		1.0		1.0		5,380
		Separate smoking areas	23	1.04	0.94–1.14	1.05	0.88–1.26	1.09	0.77–1.55	4,992
		Smoke-free in school buildings	19	0.99	0.89–1.09	1.23	1.03–1.47	1.44	1.02–2.02	4,275
		Smoke-free throughout school site	27	0.94	0.85–1.03	1.01	0.85–1.20	0.98	0.69–1.38	6,032
	Senior	Insufficient separation of smoking	19	1.0		1.0		1.0		8,569
		Separate smoking areas	28	0.91	0.86–0.96	0.89	0.82–0.96	0.88	0.80–0.97	10,649
		Smoke-free in school buildings	13	0.80	0.74–0.86	0.70	0.63–0.77	0.64	0.56–0.73	4,590
		Smoke-free throughout school site	27	0.87	0.79–0.89	0.76	0.70–0.82	0.69	0.63–0.77	11,511
Female	Junior	Insufficient separation of smoking	23	1.0		1.0		1.0		4,606
		Separate smoking areas	23	1.15	1.02–1.29	1.06	1.02–1.29	1.69	1.02–2.81	4,558
		Smoke-free in school buildings	19	1.16	1.03–1.31	1.31	1.03–1.31	1.33	0.76–2.32	3,882
		Smoke-free throughout school site	27	0.87	0.78–0.98	0.75	0.78–0.98	0.84	0.48–1.48	5,660
	Senior	Insufficient separation of smoking	19	1.0		1.0		1.0		5,222
		Separate smoking areas	28	0.81	0.75–0.88	0.92	0.81–1.04	0.83	0.68–1.00	10,139
		Smoke-free in school buildings	13	1.12	1.01–1.23	1.30	1.12–1.50	1.05	0.84–1.32	3,782
		Smoke-free throughout school site	27	0.87	0.81–0.95	0.93	0.82–1.06	0.85	0.69–1.03	8,604

OR, Odds ratio; CI, 95% confidence interval adjusted by school grade and school policy on teachers’ smoking in school

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