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Table 2 Lifetime cumulative ETS exposure in a population-based sample of adults aged 55–75 years

From: Lifetime environmental tobacco smoke exposure and the risk of chronic obstructive pulmonary disease

Source of ETS exposure

COPD (n = 386)

No COPD (n = 1,727)

P value

Prenatal ETS*

32 (8.3%)

96 (5.6%)

0.051

Cumulative lifetime home ETS

  

<0.0001

   Quartile 1 (0–9 yrs)

70 (18%)

443 (26%)

 

   Quartile 2 (10–21 yrs)

72 (19%)

461 (27%)

 

   Quartile 3 (22–41 yrs)

86 (22%)

451 (26%)

 

   Quartile 4 (≥42 yrs)

158 (41%)

372 (22%)

 

Cumulative lifetime work ETS

  

0.0002

   Quartile 1 & 2 (0–5 yrs)†

163 (42%)

881 (51%)

 

   Quartile 3 (6–22 yrs)

93 (24%)

440 (25%)

 

   Quartile 4 (≥23 yrs)

130 (34%)

406 (24%)

 
  1. Proportions are column proportions (of those with and without COPD)
  2. P-values from the likelihood ratio chi-square test
  3. *Mother smoked during pregnancy
  4. †First and second quartile were both zero, so they were combined into one group.