Table 1– Description of study populations of all four cohort studies as used in the chronic obstructive pulmonary disease prevalence analyses
ECRHSNSHDSALIASAPALDIA
NO2 populationPM populationNO2 populationPM populationNO2 populationPM populationNO2 populationPM population
Subjects n319415838447515805801764729
Female1613 (50.5)830 (52.4)471 (55.81)418 (55.6)580 (100)580 (100)980 (55.5)422 (57. 9)
Age at baseline#34.3±7.235.1±7.153.4±0.253.4±0.254.3±0.854.3±0.842.4±11.043.0±10.8
Age at follow-up43.0±7.243.9±7.163.3±1.163.3±1.173.3±3.473.3±3.453.2±11.053.9±10.7
BMI at follow-up kg·m−325.4±4.324.8±4.327.7±4.927.7±5.027.4±4.527.4±4.525.4±4.325.1±4.3
Smoking status at baseline
 Never-smoker1390 (43.5)707 (44.7)270 (32.0)230 (30.6)459 (79.1)459 (79.1)704 (39.9)291 (39)
 Ex-smoker691 (21.6)494 (31.2)437 (51.8)396 (52.7)61 (10.5)61 (10.5)568 (32.2)219 (30.0)
 Current smoker1113 (34.8)382 (24.1)137 (16.2)125 (16.6)60 (10.3)60 (10.3)492 (27.9)219 (30.0)
Pack years smoked by ever-smokers at baseline7.5±11.67.4±12.29.1±12.69.3±12.62.8±8.42.8±8.410.9±17.911.8±19.3
Pack years smoked during the follow-up by ever-smokers3.7±10.52.7±10.70.7±2.50.7±2.50.6±6.70.6±6.73.1±6.53.5±6.8
Educational level
 Low758 (23.7)363 (22.9)303 (35.9)275 (36.6)105 (18.1)105 (18.1)130 (5.8)46 (6.3)
 Medium1064 (33.3)513 (32.4)439 (52.0)394 (52.5)276 (47.6)276 (47.6)1121 (63.55)510 (70.0)
 High1372 (50.0)707 (44.7)102 (12.1)82 (10.9)199 (34.3)199 (34.3)520 (29.5)172 (23.6)
ETS+555 (17.4)259 (16.4)168 (19.9)144 (19.2)347 (59.8)347 (59.8)119 (6.8)40 (5.5)
Occupational exposure§1360 (43.4)549 (35.7)246 (29.1)220 (29.3)39 (6.7)39 (6.7)460 (26.1)143 (19.6)
Asthma at baseline229 (7.2)143 (9.1)44 (5.2)37 (4.9)9 (1.6)9 (1.6)130 (7.4)43 (5.9)
Asthma at follow-up334 (10.5)191 (12.1)83 (9.8)68 (9.1)47 (8.1)47 (8.1)153 (8.7)48 (6.6)
  • Subpopulations of the original studies with individually assigned NO2 and particulate matter (PM) measures, respectively. Data are presented as n (% of total N) for categorical variables, and mean±sd in case of continuous variables. BMI: body mass index; ETS: environmental tobacco smoke. #: age at lung function testing; : maximal reached educational level at baseline and follow-up; +: exposure at home or at work at follow-up; §: exposure to dust/fumes or gases at follow-up (yes/no).