Table 3.
Ratio (95% CI) of the geometric mean of hair nicotine concentrations by air nicotine concentrations and other characteristics*
| Non-smoking employees | Smoking employees | |||||
|---|---|---|---|---|---|---|
| N | Crude | Adjusted | N | Crude | Adjusted | |
| Air nicotine (µg/m3) | ||||||
| < 1.3 | 203 | 1.00 (reference) | 1.00 (reference) | 109 | 1.00 (reference) | 1.00 (reference) |
| 1.3– 5.2 | 210 | 2.51 (1.86, 3.37) | 2.54 (1.91, 3.39) | 105 | 1.67 (1.08, 2.57) | 1.55 (1.03, 2.34) |
| > 5.2 | 212 | 3.42 (2.35, 4.99) | 3.77 (2.62, 5.42) | 97 | 1.55 (0.94, 2.55) | 1.53 (0.95, 2.46) |
| P-value for trend | <0.0001 | <0.0001 | 0.04 | 0.02 | ||
| Per doubling of air nicotine | 625 | 1.30 (1.22, 1.38) | 1.30 (1.23, 1.38) | 311 | 1.09 (1.00, 1.19) | 1.10 (1.02, 1.19) |
| Sex | ||||||
| Men | 302 | 1.00 (reference) | 1.00 (reference) | 169 | 1.00 (reference) | 1.00 (reference) |
| Women | 323 | 0.48 (0.38, 0.63) | 0.57 (0.43, 0.75) | 142 | 0.44 (0.31, 0.63) | 0.67 (0.45, 0.99) |
| Age (years) | ||||||
| < 26 | 310 | 1.00 (reference) | 1.00 (reference) | 137 | 1.00 (reference) | 1.00 (reference) |
| ≥ 26 | 315 | 0.93 (0.73, 1.18) | 0.92 (0.73, 1.15) | 172 | 1.13 (0.81, 1.57) | 1.18 (0.85, 1.62) |
| Region | ||||||
| Americas | 142 | 1.00 (reference) | 1.00 (reference) | 127 | 1.00 (reference) | 1.00 (reference) |
| Eastern Europe | 157 | 0.88 (0.35, 2.23) | 0.55 (0.26, 1.18) | 78 | 0.41 (0.17, 0.99) | 0.45 (0.21, 0.97) |
| Asia | 240 | 2.34 (1.00, 5.50) | 1.62 (0.81, 3.21) | 98 | 1.76 (0.77, 4.04) | 1.81 (0.89, 3.67) |
| Africa | 86 | 1.34 (0.36, 4.98) | 1.25 (0.44, 3.53) | 8 | 1.85 (0.41, 8.48) | 1.32 (0.35, 4.95) |
| Education | ||||||
| ≤ High school | 410 | 1.00 (reference) | 1.00 (reference) | 179 | 1.00 (reference) | 1.00 (reference) |
| > High school | 212 | 0.72 (0.54, 0.95) | 0.79 (0.61, 1.02) | 130 | 0.98 (0.69, 1.39) | 0.95 (0.68, 1.32) |
| Living with a smoker | ||||||
| No | 352 | 1.00 (reference) | 1.00 (reference) | 147 | 1.00 (reference) | 1.00 (reference) |
| Yes | 265 | 1.11 (0.86, 1.43) | 1.14 (0.90, 1.44) | 159 | 1.10 (0.80, 1.53) | 1.12 (0.82, 1.53) |
| Hair treatment | ||||||
| Yes | 285 | 1.00 (reference) | 1.00 (reference) | 142 | 1.00 (reference) | 1.00 (reference) |
| No | 333 | 1.85 (1.46, 2.34) | 1.40 (1.08, 1.81) | 160 | 2.44 (1.76, 3.38) | 2.14 (1.49, 3.07) |
*
Estimated using mixed-effect models that allow for country specific intercepts.
Air nicotine models were adjusted for age (< 26, ≥ 26 y), sex, education (≤ high school, > high school), living with a smoker, hair treatment, region and for former smoking status for non-smokers. Other variables were further adjusted for air nicotine concentrations (log2-transformed).
P-value for trend assumes a log-log relationship between air and hair nicotine concentrations.