Table 4.
The combined effects between ambient fine particulate matter pollution (PM2.5) exposure and smoking on the risk of depressive symptoms
| Odds ratios (95% CI) |
||
|---|---|---|
| Category | Crude | Adjusteda |
| PM2.5–smoking status | ||
| Low–non-smoker | 1.00 | 1.00 |
| Low–smoker | 1.10 (0.98–1.22) | 1.23 (1.09–1.39) |
| High–non-smoker | 1.27 (1.09–1.48) | 1.29 (1.09–1.51) |
| High–smoker | 1.42 (1.21–1.67) | 1.64 (1.38–1.95) |
| Synergy index | 1.16 | 1.23 |
| P for multiplicative interaction | 0.76 | 0.67 |
| PM2.5–smoking frequency | ||
| Low–non-smoking | 1.00 | |
| Low–occasional | 1.25 (1.06–1.47) | 1.33 (1.12–1.59) |
| Low–daily | 1.02 (0.90–1.16) | 1.18 (1.02–1.35) |
| High–non-smoking | 1.27 (1.09–1.48) | 1.29 (1.09–1.51) |
| High–occasional | 1.45 (1.19–1.76) | 1.70 (1.38–2.09) |
| High–daily | 1.41 (1.19–1.67) | 1.61 (1.34–1.93) |
| Synergy indexb | 1.42 | 1.32 |
| P for multiplicative interaction | 0.44 | 0.57 |
| PM2.5–smoking duration | ||
| Low–non-smoking | 1.00 | 1.00 |
| Low–short | 1.03 (0.83–1.29) | 1.25 (0.98–1.59) |
| Low–long | 1.04 (0.90–1.19) | 1.12 (0.96–1.32) |
| High–non-smoking | 1.25 (1.07–1.46) | 1.27 (1.08–1.49) |
| High–short | 1.25 (1.00–1.56) | 1.45 (1.15–1.84) |
| High–long | 1.50 (1.25–1.79) | 1.63 (1.34–1.98) |
| Synergy indexb | 1.76 | 1.61 |
| P for multiplicative interaction | 0.14 | 0.22 |
| PM2.5–smoking amount | ||
| Low–non-smoking | 1.00 | 1.00 |
| Low–small | 1.13 (0.99–1.28) | 1.20 (1.07–1.33) |
| Low–large | 1.04 (0.8–1.22) | 1.33 (1.15–1.52) |
| High–non-smoking | 1.27 (1.09–1.48) | 1.28 (1.12–1.47) |
| High–small | 1.44 (1.22–1.71) | 1.56(1.34–1.82) |
| High–large | 1.39(1.15–1.68) | 1.78 (1.51–2.11) |
| Synergy indexb | 1.26 | 1.28 |
| P for multiplicative interaction | 0.72 | 0.66 |
a.
Adjusted for age, gender, body mass index, alcohol drinking, marital status, urbanity, household income, education level, domestic fuel type and ventilation.
b.
The synergy index for PM2.5 with smoking frequency, duration and amount was for the combination of high PM2.5 exposure with highest levels of smoking variables (smoking daily, more than 15 years and more than eight cigarette equivalents per day).