Table 1 Baseline characteristics of the civil servants cohort according to quintiles of average PM_2.5 concentration during 1989–2008

No. of participants

5,520

3,847

8,267

19,004

6,589

Range of average PM_2.5 concentration, μg/m³

22.8–27.2

27.3–28.6

28.7–30.0

30.1–30.9

31.5–32.9

Mean PM_2.5 in μg/m³ (SD)

25.8 (1.4)

28.3 (0.4)

29.6 (0.4)

30.4 (0.3)

32 (0.4)

Female sex (%)

47.3

38.7

39.2

44.5

42.6

Less than high-school education (%)

1.9

1.7

2.3

1.8

2.6

 Married (%)

45.7

41.1

39.3

39.2

37.9

 Other (%)

54.3

58.9

60.7

60.8

62.1

  ≤ $ 30,000

8.6

10.1

10.5

7.1

11.2

 $30,000-60,000

45.9

52.1

51.7

43

51.7

 $60,000-100,000

37.3

31.8

32.1

39.4

31.2

  > $100,000

8.2

6.1

5.8

10.5

5.9

Average age at recruitment in years (SD)

40.6 (10.4)

40.6 (10.7)

40.4 (10.4)

42.5 (10.5)

39.7 (10.8)

 Never

52.2

47.4

48.4

47.7

49.7

 Former

7.7

8

8.2

7.5

7

 Current

40.1

44.6

43.4

44.8

43.3

Habitual alcohol consumption (%)

72.4

75.3

73.7

74.6

73

Average body-mass index^a, %

22.7

23.1

23.9

22.8

22.8

  < 20.1

19

14.8

16.7

16.9

17.9

 20.1-27.5

75.1

78.6

76.6

77.7

76

  > 27.5

5.9

6.7

6.7

5.4

6.1

Serum triglyceride level (mg/dL)

113

116

116

113

117

Serum total cholesterol level (mg/dL)

197

194

195

197

197

Diabetes mellitus (%)

2.2

1.8

1.7

2.1

1.7

Hypertension (%)

9

9.8

9.6

10.2

8.9

History of cerebrovascular disease (%)

0.4

0.3

0.4

0.3

0.3

History of heart disease (%)

4.4

5

5

5.2

4.5

Average GFR^b (mL/min/1.73 m²)

83

83

82.8

83.1

82.9