Number	(percent)
Gender
Male	769	(51.3)
Female	731	(48.7)
Age, M (SD)	40.31	(10.92)
Education
High school or lower	235	(15.7)
Some college	88	(5.9)
Associate’s or bachelor’s degree	1,020	(68.0)
Graduate school	21	(1.4)
Graduate degree	136	(9.1)
Income (Korean Won)
< 1.99 million	179	(11.9)
2.00-3.99 million	477	(31.8)
4.00-5.99 million	479	(32.0)
6.00-10.00 million	310	(20.6)
> 10.00 million	55	(3.7)
Respiratory diseases experience
Yes	149	(9.9)
No	1,351	(90.1)
N	1,500	(100)