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Table 1 Descriptive statistics of the study cohort and PM2.5 exposure, with Cox proportional HRs for each covariate

From: Risk estimates of mortality attributed to low concentrations of ambient fine particulate matter in the Canadian community health survey cohort

    95 % C.I. PM2.5
Covariate Persons+ HRǂ Lower Upper Mean SD
All 299,500 6.32 2.54
Sex       
  Male 137,800 6.28 2.54
  Female 161,700 6.36 2.54
Age group†       
  25–34 years 52,500 6.39 2.54
  35–44 years 59,400 6.29 2.50
  45–54 years 58,100 6.21 2.51
  55–64 years 54,900 6.20 2.51
  65–74 years 41,700 6.41 2.58
  75–90 years 32,900 6.58 2.64
Immigrant status       
  Not an immigrant 270,300 1.000 6.19 2.50
  Immigrant (in Canada ≥ 20 years) 28,800 *0.863 0.834 0.894 7.57 2.52
Visible minority status       
  White 281,000 1.000 6.31 2.53
  Visible minority 17,700 0.938 0.877 1.004 6.49 2.67
Aboriginal status       
  Not Aboriginal 289,600 1.000 6.36 2.54
  Aboriginal 9,200 *1.390 1.267 1.525 5.12 2.21
Marital status       
  Married or common-law 183,500 1.000 6.09 2.46
  Separated, divorced, widowed 69,500 *1.344 1.306 1.382 6.62 2.60
  Single, never married 46,400 *1.512 1.446 1.581 6.82 2.63
Educational attainment       
  Not completed high school 71,700 1.000 6.01 2.58
  High school diploma 113,500 *0.829 0.806 0.852 6.25 2.50
  Post-secondary diploma/certificate 64,900 *0.723 0.694 0.753 6.43 2.51
  University degree 47,100 *0.581 0.552 0.611 6.83 2.51
Low income adequacy quintile       
  1st quintile - lowest 56,200 1.000 6.53 2.64
  2nd quintile 54,500 *0.787 0.762 0.813 6.37 2.58
  3rd quintile 53,000 *0.662 0.637 0.689 6.37 2.52
  4th quintile 53,300 *0.583 0.557 0.610 6.34 2.49
  5th quintile - highest 56,700 *0.483 0.458 0.509 6.17 2.43
Employment status       
  Employed 174,500 1.000 6.31 2.50
  Not employed: looked for work‡ 7,300 *1.522 1.319 1.757 6.20 2.61
  Not employed: did not look for work‡ 78,100 *1.818 1.732 1.908 6.25 2.55
  Permanently unable to work 9,800 *4.533 4.274 4.808 6.43 2.64
Body Mass Indexa       
  Underweight (<18.5) 3,700 *2.140 1.989 2.303 6.76 2.60
  Normal weight (18.5 - 25.0) 93,700 1.000 6.54 2.55
  Overweight (25.0 - 30.0) 114,900 *0.804 0.781 0.828 6.29 2.52
  Obese I (30.0 - 35.0) 54,700 *0.884 0.852 0.917 6.14 2.52
  Obese II (>35.0) 24,200 *1.270 1.209 1.334 6.06 2.53
Fruit and vegetable consumption       
  <5 servings per day 153,200 1.000 6.38 2.56
  ≥5 servings per day 101,100 *0.828 0.806 0.851 6.52 2.52
Smoking       
  Never smoked 84,100 1.000 6.41 2.53
  Former smoker 139,200 *1.284 1.244 1.324 6.26 2.51
  Current daily or occasional smoker 75,900 *2.604 2.509 2.702 6.33 2.59
Alcohol       
  Regular drinker (≥1 drink per month) 141,700 1.000 6.51 2.55
  Occasional or former drinker 80,800 *1.394 1.356 1.433 6.25 2.59
  Never drinker 11,000 *1.274 1.214 1.337 6.17 2.64
Ecological covariatesb       
  % recent immigrants (CD-DA) *1.102 1.064 1.141
  % recent immigrants (CD) *0.713 0.680 0.747
  % completed high school (CD-DA) *0.928 0.919 0.938
  % completed high school (CD) *0.897 0.886 0.908
  % in low income families (CD-DA) *1.119 1.107 1.131
  % in low income families (CD) *1.100 1.070 1.131
  1. +Numbers were rounded to the nearest 100 for confidentiality
  2. ǂModels were stratified by age (5 year categories) and sex
  3. *Significant HR (p < 0.05)
  4. †At time of entry into the cohort
  5. ‡(Did not) look for work in past 4 weeks
  6. aAfter adjusting for self-reporting bias in CCHS, as in [16]
  7. bHRs provided for 10 % increase in population