Table 5. Characteristics of baseline study subjects (Cohort 1 in 2015).

Characteristics at baseline 2015	na	%
Total	8,240	100.0
Sex
Men	4,084	49.6
Women	4,156	50.4
Age groups, years
15–19	881	10.7
20–29	1,462	17.7
30–39	1,465	17.8
40–49	1,487	18.1
50–59	1,461	17.7
60–69	1,484	18.0
Smoking status
Never-smoker	4,839	58.7
Former smoker	1,582	19.2
Current smoker with intention to quit	281	3.4
Current smoker with no intention to quit	1,538	18.7
Workplace indoor smoking ban status
No ban (including smoking room/corner)	2,699	32.8
Complete ban	3,256	39.5
Not working/did not know	2,285	27.7
Heat-not-burn-tobacco/e-cigarette use status
Never used with no preference for e-cigarette use	7,369	89.4
Never used, but would like to try e-cigarette in future	353	4.3
Ever-user	518	6.3
Equivalent household income
1st quartile (Lowest)	2,079	25.2
2nd quartile	1,646	20.0
3rd quartile	1,531	18.6
4th quartile (Highest)	1,256	15.2
Did not know/did not want to answer	1,729	21.0
Housing tenure
Does not own housing	2,237	27.2
Owns housing	6,003	72.9
Education
Junior high school/high school	4,905	59.5
University/technical school/college or higher	3,335	40.5
Marital status
Married	4,970	60.3
Never married	2,802	34.0
Divorced/widowed	468	5.7
Alcohol consumption
Never-drinker	3,360	40.8
Former drinker	473	5.8
Current drinker	4,406	53.5
Self-rated health
Good (excellent/very good/good)	7,356	89.3
Poor (fair/poor)	884	10.7

^aAdjusted for “being a respondent in an internet survey” using weights to make the cohorts representative of the national general population in Japan.