Table 1:

Participant characteristics

CharacteristicsNo. (%) of patients at baseline*
n = 384 130
No. (%) of observations*
n = 842 394
No. (%) of deaths from natural causes (mortality rate, per 1000 person-years)
n = 12 375 (2.5)
Age, yr, mean ± SD39.2 ± 12.741.6 ± 12.5
Sex, male186 985 (48.7)424 495 (50.4)7206 (3.1)
Education
 Lower than high school56 862 (14.8)110 341 (13.1)7014 (9.4)
 High school75 248 (19.6)159 295 (18.9)2268 (2.3)
 College or university204 730 (53.3)459 089 (54.5)2753 (1.1)
 Postgraduate47 290 (12.3)113 669 (13.5)340 (0.6)
Cigarette smoking
 Never284 311 (74.0)635 672 (75.5)7671 (2.1)
 Former21 944 (5.7)50 776 (6.0)1361 (5.1)
 Current77 875 (20.3)155 946 (18.5)3343 (3.4)
Alcohol consumption
 Never or seldom330 179 (86.0)720 674 (85.6)10 002 (2.4)
 Former36 063 (9.4)82 329 (9.8)1048 (2.3)
 Current17 888 (4.7)39 391 (4.7)1325 (5.9)
Physical labour at work
 Mostly sedentary242 748 (63.2)556 806 (66.1)7559 (2.5)
 Sedentary with occasional walking100 314 (26.1)208 090 (24.7)3095 (2.4)
 Mostly standing or walking33 123 (8.6)63 685 (7.6)1372 (3.3)
 Hard labour7945 (2.1)13 813 (1.6)349 (3.5)
Habitual exercise group
 Inactive173 948 (45.3)323 617 (38.4)5290 (2.3)
 Moderate113 669 (29.6)266 415 (31.6)1904 (2.3)
 High96 513 (25.1)252 362 (30.0)5181 (3.0)
Exercise, MET-h, mean ± SD7.2 ± 13.08.5 ± 14.2
Vegetable intake
 Seldom54 200 (14.1)99 349 (11.8)2005 (2.9)
 Moderate226 735 (59.0)493 825 (58.6)7083 (2.5)
 Frequent103 195 (26.9)249 220 (29.6)3287 (2.6)
Fruit intake
 Seldom132 705 (34.5)249 169 (29.6)4164 (2.6)
 Moderate206 117 (53.7)477 307 (56.7)6747 (2.6)
 Frequent45 308 (11.8)115 918 (13.8)1464 (2.5)
Occupational exposure31 146 (8.1)66 118 (7.8)745 (1.9)
Body mass index (kg/m2), mean ± SD23.0 ± 3.723.2 ± 3.6
PM2.5 (μg/m3), mean ± SD26.4 ± 7.626.3 ± 7.4
PM2.5 by exercise group, mean ± SD
 Inactive26.6 ± 7.626.6 ± 7.5
 Moderate26.3 ± 7.526.2 ± 7.4
 High26.2 ± 7.626.0 ± 7.4
  • Note: MET = metabolic equivalent, PM2.5 = fine particle matter, SD = standard deviation.

  • * Unless indicated otherwise.

  • The tertile cut-off points for exercise volume using the MET value and duration (h): inactive (0 MET-h), moderate (0 to 8.75 MET-h) and high (> 8.75 MET-h). The tertile cut-off points for PM2.5: low (< 22.4 μg/m3), moderate (22.4 to 26.0 μg/m3) and high (≥ 26.0 μg/m3).

  • Refers to the 2-year average PM2.5 concentration in the year of medical visit and in the year before the medical visit.