Directly measured secondhand smoke exposure and COPD health outcomes

BMC Pulmonary Medicine

Table 2 Distribution of SHS exposure among non-smokers with COPD by self-report and direct exposure monitoring

Measure	N	Proportion with any self-reported exposure or detectable urine/badge level	SHS exposure among those with any exposure
			25^th %tile	Median	75^th %tile
Self-report, past 7 days (hrs)	77	20 (26%)	1	2	7
Urine cotinine (ng/ml)	77	69 (90%)	0.092	0.20	0.81
First tertile*	26	14 (54%)	0	0.054	0.069
Second tertile	26	26 (100%)	0.12	0.16	0.22
Third tertile	25	25 (100%)	0.75	1.54	3.86
Personal nicotine badge (μg/m³)	77	64 (83%)	0.096	0.22	0.63
First tertile*	27	14 (52%)	0	0.023	0.061
Second tertile	24	24 (100%)	0.12	0.14	0.22
Third tertile	26	26 (100%)	0.45	0.86	1.53

*Based on the distribution, urine cotinine and personal badge nicotine levels were divided into tertiles for statistical analysis. Although lowest tertile contained some subjects with detectable values, these were very low values quantitatively.
Among 77 subjects with all three measures available, the Spearman rank correlation between self-reported SHS exposure and urine cotinine was 0.28 (p = 0.013); between self-reported exposure and badge nicotine level was 0.06 (p = 0.57); between urine cotinine and badge nicotine was 0.41 (p = 0.0002). When tertile of urine cotinine and nicotine badge were examined as categories, the Kappa was 0.33 (95% CI 0.16 to 0.50).

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