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Table 2 Cotinine concentration distribution and proportion of 10-11 year old children in Wales above each cut-point pre- and post-legislation

From: Changes in child exposure to secondhand smoke after implementation of smoke-free legislation in Wales: a repeated cross-sectional study

Measurement

2007(n = 1447)

2008(n = 1461)

p-value

Median cotinine concentration

0.10

0.10

-

Percentage below level of detection (0.1 ng/ml)

43.98

49.90

-

Percentage above cotinine concentration (ng/ml)

   

0.1*

56.04

50.10

-

0.2

40.15

39.22

-

0.5

31.44

28.82

-

1

22.88

20.33

-

1.7

14.38

13.48

-

2

12.30

10.95

-

3

7.41

5.57

-

Unadjusted geometric mean (95% CI) cotinine concentration (ng/ml)**

0.17

(0.14 to 0.20)

0.15

(0.13 to 0.18)

0.10

Geometric mean (95% CI) cotinine concentration (ng/ml) adjusted for age, family affluence and time of day data collected**

0.17

(0.15 to 0.20)

0.15

(0.13 to 0.17)

0.07

  1. *including 0.1
  2. ** non-smoking children only