Associations between exposure to PM2.5 and semen quality
| Semen parameters (n=6475) | Crude model* | Model 1* | Model 2* | Model 3* | ||||
| Coef/OR (95% CI)† | p Value | Coef/OR (95% CI)† | p Value | Coef/OR (95% CI)† | p Value | Coef/OR (95% CI)† | p Value | |
| Short-term exposure (3-month average PM2.5) | ||||||||
| Continuous | ||||||||
| Concentration (106/mL)‡ | 1.04 (1.03 to 1.05) | <0.001 | 1.04 (1.02 to 1.05) | <0.001 | 1.04 (1.02 to 1.05) | <0.001 | 1.03 (1.02 to 1.05) | <0.001 |
| Total motility (%) | 0.28 (0.07 to 0.49) | 0.008 | 0.18 (−0.02 to 0.39) | 0.08 | 0.18 (−0.02 to 0.39) | 0.08 | 0.19 (−0.02 to 0.41) | 0.07 |
| Progressive motility (%) | −0.02 (−0.25 to 0.21) | 0.86 | −0.08 (−0.31 to 0.15) | 0.49 | −0.07 (−0.30 to 0.16) | 0.55 | −0.05 (−0.29 to 0.19) | 0.68 |
| Normal morphology (%) | 0.70 (-0.91 to –0.49) | <0.001 | −0.78 (−1.00 to –0.57) | <0.001 | −0.79 (−1.00 to –0.58) | <0.001 | −0.91 (−1.13 to –0.69) | <0.001 |
| Dichotomous (<10th percentile as decreased) | ||||||||
| Decreased concentration | 0.88 (0.83 to 0.93) | <0.001 | 0.88 (0.83 to 0.93) | <0.001 | 0.88 (0.83 to 0.93) | <0.001 | 0.90 (0.85 to 0.95) | <0.001 |
| Decreased total motility | 0.94 (0.89 to 0.99) | 0.02 | 0.95 (0.90 to 1.01) | 0.10 | 0.95 (0.90 to 1.01) | 0.10 | 0.97 (0.91 to 1.02) | 0.27 |
| Decreased progressive motility | 0.96 (0.92 to 1.01) | 0.16 | 0.98 (0.93 to 1.03) | 0.42 | 0.98 (0.93 to 1.03) | 0.44 | 1.00 (0.95 to 1.05) | 0.94 |
| Decreased normal morphology | 1.16 (1.11 to 1.21) | <0.001 | 1.17 (1.12 to 1.22) | <0.001 | 1.17 (1.12 to 1.22) | <0.001 | 1.18 (1.13 to 1.24) | <0.001 |
| Long-term exposure (2-year average PM2.5) | ||||||||
| Continuous | ||||||||
| Concentration (106/mL)‡ | 1.03 (1.02 to 1.05) | <0.001 | 1.03 (1.02 to 1.05) | <0.001 | 1.03 (1.02 to 1.05) | <0.001 | 1.03 (1.02 to 1.05) | <0.001 |
| Total motility (%) | 0.45 (0.21 to 0.69) | <0.001 | 0.32 (0.09 to 0.57) | 0.008 | 0.33 (0.09 to 0.57) | 0.007 | 0.34 (0.10 to 0.581) | 0.006 |
| Progressive motility (%) | 0.13 (−0.14 to 0.40) | 0.35 | 0.05 (−0.22 to 0.32) | 0.71 | 0.07 (−0.20 to 0.33) | 0.64 | 0.11 (−0.16 to 0.38) | 0.43 |
| Normal morphology (%) | −1.17 (−1.42 to –0.92) | <0.001 | −1.28 (−1.53 to –1.04) | <0.001 | −1.29 (−1.54 to –1.05) | <0.001 | −1.29 (−1.53 to –1.04) | <0.001 |
| Dichotomous (<10th percentile as decreased) | ||||||||
| Decreased concentration | 0.90 (0.85 to 0.96) | <0.001 | 0.90 (0.85 to 0.96) | 0.001 | 0.90 (0.85 to 0.96) | 0.001 | 0.90 (0.85 to 0.96) | 0.001 |
| Decreased total motility | 0.90 (0.84 to 0.96) | <0.001 | 0.92 (0.86 to 0.98) | 0.01 | 0.92 (0.86 to 0.98) | 0.01 | 0.92 (0.86 to 0.99) | 0.02 |
| Decreased progressive motility | 0.93 (0.88 to 0.99) | 0.03 | 0.95 (0.89 to 1.01) | 0.11 | 0.95 (0.89 to 1.01) | 0.11 | 0.95 (0.90 to 1.01) | 0.12 |
| Decreased normal morphology | 1.24 (1.18 to 1.31) | <0.001 | 1.26 (1.20 to 1.33) | <0.001 | 1.26 (1.20 to 1.33) | <0.001 | 1.26 (1.20 to 1.33) | <0.001 |
Effect estimates were calculated for an increment of 5 µg/m3 in PM2.5 concentrations.
*Crude model had no adjustment; model 1 was adjusted for age, educational level, smoking status, alcohol drinking, exercise and occupational exposure to asbestos and organic solvent; model 2 was further adjusted for body mass index, systolic blood pressure, fasting blood glucose and total cholesterol levels; model 3 was further adjusted for season and year of medical examination.
†Beta-coefficients were presented for continuous variables and ORs were presented for dichotomous variables.
‡Concentration was log-transformed to achieve approximate normality for the data analysis and then the geometric coefficients were transformed back for presentation.
Coef, coefficients; PM2.5, particulate matter with an aerodynamic diameter <2.5 µm.