Table 1 Demographic characteristics and risk factors for hypertension in the three study groups

Subjects (no.)

214

302

274

Age (years)

   Mean (SD)

41.4 (7.1)^{d, e}

38.1 (5.6)

37.4 (6.7)

< 0.001^a

Environmental noise (dBA)

   Mean (SD)

83.1 (4.9)^d

83.1 (4.4)^d

82.2 (5.1)

< 0.001^a

Employment duration (years)

   Mean (SD)

10.4 (6.0)

9.8 (5.1)

9.1 (5.4)

0.192^a

Body Mass Index (kg/m²)

   Mean (SD)

24.4 (3.2)

23.9 (3.0)

24.0 (3.2)

0.250^a

Total cholesterol level (mg/dL)

   Mean (SD)

185.7 (33.1)

188.4 (38.5)

183.4 (35.4)

0.372^a

Triglyceride level (mg/dL)

   Mean (SD)

153.2 (100.6)

147.2 (69.5)

149.9 (84.9)

0.584^a

Educational level

   < 12 years (%)

143 (66.8)

177 (58.6)

180 (65.7)

0.096^b

Tobacco use

   Yes (%)

118 (55.1)

154 (51.0)

157 (57.3)

0.304^b

Alcohol consumption

   Yes (%)

134 (62.6)

180 (59.6)

177 (64.6)

0.460^b

Regular exercise

   Yes (%)

71 (33.2)

90 (29.8)

90 (32.9)

0.643^b

Disease history of hypertension

   Yes (%)

5 (2.3)

4 (1.3)

1 (0.4)

0.165^c

Use of PPE at work

   Never (%)

76 (35.5)^f

108 (35.8)^f

150 (54.7)

< 0.001^b

   < 2 hours working time (%)

36 (16.8)

68 (22.5)

50 (18.3)

   2-4 hours working time (%)

35 (16.4)

39 (12.9)

31 (11.3)

   > = 4 hours working time (%)

67 (31.3)

87 (28.8)

43 (15.7)