1.

调查对象的人口学特征(n=8 021)

Demographic characters of the study participants (n=8 021)

Items	n	Constituent ratio/%
BMI, body mass index. Factory A, an electrical equipment manufacturing plant; Factory B, an automobile factory; Factory C, a shipyard; Factory D, a steel machinery manufacturing plant.
Gender
Male	6 170	76.9
Female	1 804	22.5
Age
18 years old-	1 048	13.1
26 years old-	2 862	35.7
36 years old-	2 906	36.2
46 years old-	1 205	15.0
Education level
≤Middle school	1 356	16.9
High school	4 531	56.5
≥College/University	2 134	26.6
BMI
<18.5 kg/m2	459	5.7
18.5 kg/m2-	5 107	63.7
24 kg/m2-	2 113	26.3
28 kg/m2-	342	4.3
Job tenure
<5 years old	2 042	25.5
5 years old-	1 581	19.7
10 years old-	1 337	16.7
15 years old-	1 058	13.2
20 years old-	1 763	22.0
Factory
A	1 752	21.8
B	3 876	48.3
C	1 723	21.5
D	670	8.4