Odds ratio for airflow obstruction (LLN definition) by certain baseline characteristics in female never-smokers
| Variable | Subjects n | AFO % | Crude OR (95% CI) | Adjusted OR (95% CI) |
| Annual income yuan | ||||
| <4999 | 2858 | 10.5 | 2.29 (2.20–2.38) | 1.68 (1.61–1.76) |
| 5000–9999 | 3943 | 7.1 | 1.48 (1.44–1.53) | 1.43 (1.38–1.49) |
| 10 000–19 999 | 4586 | 5.4 | 1.11 (1.08–1.14) | 1.26 (1.22–1.30) |
| 20 000–34 999 | 3142 | 4.4 | 0.90 (0.87–0.93) | 1.01 (0.97–1.05) |
| ≥35 000 | 2377 | 4.9 | 1.00 (0.96–1.04) | 1.00 (0.95–1.05) |
| Ever diagnosed with TB | ||||
| No | 16 609 | 5.8 | 1.00 | 1.00 |
| Yes | 297 | 9.5 | 2.08 (1.82–2.37) | 2.25 (1.98–2.55) |
| Current exposure to smoking from cooking# | ||||
| Gas/electricity only | 6077 | 4.9 | 1.00 (0.97–1.03) | 1.00 (0.95–1.05) |
| Coal | 5016 | 6.4 | 1.34 (1.30–1.38) | 1.06 (1.02–1.11) |
| Wood | 4391 | 7.3 | 1.54 (1.49–1.59) | 0.91 (0.88–0.94) |
| Other | 60 | 2.8 | 0.56 (0.43–0.73) | 0.64 (0.49–0.83) |
| History of exposure to smoke from cooking¶ | ||||
| Gas/electricity only | 646 | 3.4 | 1.00 (0.92–1.08) | 1.00 (0.91–1.10) |
| Coal only | 971 | 6.0 | 1.79 (1.67–1.91) | 1.30 (1.17–1.44) |
| Coal and gas/electricity | 991 | 3.7 | 1.10 (1.03–1.17) | 1.10 (1.01–1.19) |
| Wood only | 2059 | 8.4 | 2.57 (2.46–2.69) | 0.97 (0.92–1.03) |
| Wood and gas/electricity | 1929 | 8.2 | 2.52 (2.41–2.64) | 0.96 (0.91–1.02) |
| Coal and wood | 1227 | 9.1 | 2.81 (2.65–2.98) | 1.02 (0.95–1.11) |
| Coal and wood and gas/electricity | 182 | 5.3 | 1.59 (1.37–1.84) | 0.88 (0.75–1.02) |
| Other fuel combinations | 43 | 4.1 | 1.20 (0.88–1.62) | 0.92 (0.67–1.26) |
| Current exposure to smoke from heating† | ||||
| Gas/electricity/central heating only | 2365 | 4.2 | 1.00 (0.96–1.04) | 1.00 (0.92–1.08) |
| Coal | 2596 | 4.0 | 0.94 (0.90–0.98) | 0.90 (0.85–0.94) |
| Wood | 2464 | 6.0 | 1.45 (1.39–1.51) | 1.06 (1.00–1.11) |
| Other | 144 | 12.1 | 3.13 (2.63–3.72) | 2.53 (2.11–3.04) |
| History of exposure to smoke from heating§ | ||||
| Gas/electricity/central heating only | 176 | 1.7 | 1.00 (0.86–1.16) | 1.00 (0.81–1.23) |
| Coal only | 1523 | 3.8 | 2.27 (2.16–2.39) | 1.01 (0.89–1.14) |
| Coal and gas/electricity/central heating | 549 | 2.1 | 1.21 (1.11–1.32) | 1.13 (0.97–1.32) |
| Wood only | 2146 | 5.8 | 3.52 (3.37–3.68) | 1.00 (0.94–1.07) |
| Wood and gas/electricity/central heating | 200 | 5.7 | 3.43 (2.97–3.95) | 1.25 (1.07–1.47) |
| Coal and wood | 928 | 4.1 | 2.4 (2.25–2.56) | 0.81 (0.75–0.86) |
| Coal and wood and gas/electricity/central heating | 41 | 4.2 | 2.5 (1.83–3.41) | 1.36 (0.98–1.88) |
| Combinations involving other fuel types | 153 | 12.4 | 8.03 (6.78–9.52) | 2.98 (2.50–3.55) |
Methods and variable descriptions are described in the original paper [1]. LLN: lower limit of normal; AFO: airflow obstruction; TB: tuberculosis. #: amongst those who cook regularly in their current home; ¶: amongst those who have cooked regularly in all their homes; †: amongst those who heat their current house in winter; §: amongst those who have heated all their homes in winter.