Epidemiological studies have linked ambient ozone (O₃) and residential greenness to semen quality, but their interaction has rarely been explored. We conducted a nationwide cross-sectional analysis of 26,997 semen donors from 33 Chinese provinces (from 2019 to 2022), with retrospective window-specific exposure estimates across the spermatogenic cycle. O₃ and normalized difference vegetation index (NDVI) exposures were estimated using inverse distance weighting (IDW) across the full spermatogenic cycle (0-90 days) and key developmental windows. Each interquartile range (IQR, 34.46 μg/m³) increase in O₃ was associated with higher odds ratios (OR, 95 % CI) of abnormal semen volume (1.592, 1.409-1.799), progressive motility (1.478, 1.344-1.626), sperm concentration (1.568, 1.402-1.755), and total sperm count (1.716, 1.547-1.903). Consistent patterns were observed in continuous outcome models, with semen volume (β= -0.004), progressive motility (β= -0.002), sperm concentration (β= -0.005), and total sperm count (β= -0.009). In the combined exposure model, participants with high O₃ and low NDVI exposure had the highest risk of abnormal semen quality compared with those with low O₃ and high NDVI exposure. Additive interaction analyses based on binary outcomes suggested an antagonistic interaction pattern between O₃ and NDVI for progressive motility and total sperm count, with consistently negative estimates on the additive scale. By incorporating exposures at different developmental stages, we found that O₃ and NDVI exposures during the sperm development period (70-90 days before semen collection) showed the strongest associations with abnormal semen quality. Overall, O₃ exposure was associated with impaired semen quality, while higher residential greenness appeared to attenuate these associations on the additive scale and during sensitive exposure windows.
Zhu et al. (Thu,) studied this question.