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Table 1 Statistical description

From: Does chronic disease influence susceptibility to the effects of air pollution on depressive symptoms in China?

Variable All sample (N = 23,268) Group with chronic disease (N = 15,412) Group without chronic disease (N = 7856) Group with chronic disease VS Group without chronic disease
Mean Std. Dev. Mean Std. Dev. Mean Std. Dev. P-valuea
Air pollution emission intensity (tons per 100 million Chinese yuan)
 SO2 82.950 78.355 82.602 74.980 83.632 84.587 < 0.001
 TSP 45.571 49.025 46.510 50.816 43.729 45.253 < 0.001
Air pollution emission per unit area (tons/km2)
 SO2 6.812 8.307 6.667 8.728 7.097 7.403 < 0.001
 TSP 3.079 3.495 2.998 3.576 3.236 3.326 < 0.001
Air pollution emission per capita (tons/10,000 people)
 SO2 135.137 120.211 132.127 118.256 141.042 123.753 < 0.001
 TSP 70.938 81.064 70.173 80.964 72.440 81.243 < 0.001
Climatic indexes
 Average monthly temperature (0.1 °C) 265.990 39.353 266.038 39.678 265.894 38.710 < 0.001
 Average monthly relative humidity (%) 73.253 7.603 73.077 7.634 73.599 7.529 < 0.001
 Depressive symptoms 11.623 4.664 12.176 4.858 10.538 4.043 < 0.001
Age 60.101 9.989 61.101 9.834 58.139 10.000 < 0.001
Income (Chinese yuan/year) 8175 14,912 7970 13,343 8576 17,583 0.011
  n % n % n % P-valueb
Male 11,108 47.739 7165 46.490 3943 50.191 0.010
Unmarried 2854 12.266 1991 12.919 863 10.985 0.022
Living in urban area 9016 38.748 5947 38.587 3069 39.066 0.730
Education < 0.001
 No education 5973 25.670 4145 26.895 1828 23.269  
 No education but can read/write 4218 18.128 2946 19.115 1272 16.191  
 Primary school 5181 22.267 3498 22.696 1683 21.423  
 Junior high school and above 7896 33.935 4823 31.294 3073 39.117  
Employment status < 0.001
 Unemployed 7734 33.239 5623 36.485 2111 26.871  
 Self-employed 10,162 43.674 6710 43.537 3452 43.941  
 Wage earner 5372 23.087 3079 19.978 2293 29.188  
Insurance 0.037
 Uninsured 1455 6.253 854 5.541 601 7.650  
 NCMS and URBMI 18,635 80.089 12,389 80.385 6246 79.506  
 UEBMI 3178 13.658 2169 14.074 1009 12.844  
Health behavior  
 Current Smoker 7713 33.149 4757 30.866 2956 37.627 < 0.001
 Current Drinker 7756 33.333 4932 32.001 2824 35.947 0.005
  1. aFrequencies with percentages were presented for categorical variables. P-values were calculated by Chi square test between groups having chronic disease or not
  2. bMeans with standard deviations were presented for continuous variables, and P-values were calculated one-way ANOVA between groups having chronic disease or not