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Table 1 Characteristics of the study population, stratified by SES (n = 22, 878), n (%) or mean ± SD

From: Socioeconomic status is associated with reduced lung function in China: an analysis from a large cross-sectional study in Shanghai

   Education Level
  Total Population ≤elementary middle/high ≥college
Subjects, n (%) 22,878 (100) 8375 (36 · 6) 10,351 (45 · 2) 4152 (18 · 2)
Age, years 48 · 4 ± 16 · 4 58 · 5 ± 13 · 3 44 · 9 ± 14 · 6 36 · 8 ± 15 · 1
Female 12,195 (53 · 3) 5048 (60 · 3) 5339 (51 · 6) 1808 (43 · 6)
Smoking     
 Current 5249 (22 · 9) 2028 (24 · 2) 2636 (25 · 5) 585 (14 · 1)
 Former 878 (3 · 8) 439 (5 · 2) 349 (3 · 4) 90 (2 · 2)
 Never 16,751 (73 · 2) 5908 (70 · 5) 7366 (71 · 2) 3477 (83 · 7)
Pack-yearsa 26 · 3 ± 36 · 6 32 · 3 ± 42 · 5 23 · 3 ± 31 · 6 17 · 9 ± 30 · 0
SHS exposed 17,060 (74 · 6) 6492 (77 · 5) 7976 (77 · 1) 2592 (62 · 4)
Biomass ever users 18,214 (79 · 6) 7799 (93 · 1) 8056 (77 · 8) 2359 (56 · 8)
Low fruit/vegetable 13,683 (59 · 8) 5876 (70 · 2) 5886 (56 · 9) 1921 (46 · 3)
Mode of Transport     
 None 8 (0 · 0) 6 (0 · 1) 0 (0 · 0) 2 (0 · 1)
 Bus w/o AC 2950 (12 · 9) 1157 (13 · 8) 1323 (12 · 8) 470 (11 · 3)
 Bus with AC 3665 (16 · 0) 696 (8 · 3) 2011 (19 · 4) 958 (23 · 1)
 Scooter 2628 (11 · 5) 691 (8 · 3) 1554 (15 · 0) 383 (9 · 2)
 Taxi 128 (0 · 6) 27 (0 · 3) 70 (0 · 7) 31 (0 · 8)
 Company Car 330 (1 · 4) 57 (0 · 7) 189 (1 · 8) 84 (2 · 0)
 Private Car 1916 (8 · 4) 168 (2 · 0) 929 (9 · 0) 819 (19 · 7)
 Train 18 (0 · 1) 0 (0 · 0) 10 (0 · 1) 8 (0 · 2)
 Subway 138 (0 · 6) 5 (0 · 1) 59 (0 · 6) 74 (1 · 8)
 Walk 3219 (14 · 1) 2246 (26 · 8) 800 (7 · 7) 173 (4 · 2)
 Multiple 2709 (11 · 8) 693 (8 · 3) 1247 (12 · 1) 769 (18 · 5)
 Bike 5169 (22 · 6) 2629 (31 · 4) 2159 (20 · 9) 381 (9 · 2)
Occupation     
 Farmer 110 (0.5) 102 (1.2) 8 (0.1) 0 (0.0)
 Worker 1405 (6.1) 689 (8.2) 696 (6.7) 20 (0.5)
 Professional 5128 (22.4) 595 (7.1) 2636 (25.5) 1897 (45.7)
 Administrator 2969 (13.0) 276 (3.3) 1688 (16.3) 1005 (24.2)
 Services 1526 (6.7) 556 (6.6) 909 (8.8) 61 (1.5)
 Household 368 (1.6) 206 (2.5) 145 (1.4) 17 (0.4)
 Retired 9130 (39.9) 5443 (65.0) 3129 (30.2) 558 (13.4)
 Other 2242 (9.8) 508 (6.1) 1140 (11.0) 594 (14.3)
% FEV1 97 · 8 ± 16 · 3 96 · 1 ± 18 · 6 98 · 6 ± 14 · 9 99 · 4 ± 14 · 0
% FVC 89 · 3 ± 16 · 1 85 · 4 ± 17 · 5 90 · 8 ± 14 · 8 93 · 5 ± 14 · 4
  1. aPack years excludes never smokers