Although human studies on the hazard that air pollution represents to male reproductive health, there are wide variations in exposure concentration, key components, semen quality indicators and the identification of susceptible exposure windows. The study aimed to further explore the relationship between air pollution and semen quality and the more accurate sensitive exposure windows. We investigated a cross-sectional study consisting of 1554 fertile men from Nanjing, China and evaluated their exposure to PM10, PM2.5, CO, SO2, NO2 and O3 in the air. Multiple linear regression was utilized to estimate the correlation between weekly air pollution exposure and semen quality, as well as weighted quantile sum (WQS) regression and bayesian kernel machine regression (BKMR) for the effect of mixtures. We also established the distributed lag non-linear model to delineate exposure-lag-response relationship. Our analysis linked PM2.5 exposure at week 10 to reduced total motility (β = − 2.06, 95% CI: (− 3.71, − 0.41)) and progressive motility (β = − 1.79, 95% CI: (− 3.23, − 0.34)). WQS regression showed co-exposure inversely correlated with total motility (β = − 1.49, 95% CI: (− 2.63, − 0.35)) and progressive motility (β = − 1.27, 95% CI: (− 2.30, − 0.25)) at week 11, where PM2.5 contributed the most. A great lagged impact resulting from PM2.5 on sperm motility peaked 10 to 11 weeks after exposure. We also found that PM2.5 exposure at week 10 increased the risk of having below-referenced progressive motility (< 32%) by the method of BKMR. Based on these results, the early stage of spermatogenesis (from week 10 to week 11 before semen collection), was recognized as the susceptible exposure window. Furthermore, BKMR analysis suggested co-exposure to major components of the primary contributor, PM2.5, during this period were negatively correlated with sperm motility, including NO3−, NH4+, SO42−, black carbon and organic matter, and SO42− was the most weighted composition. In both the single pollutant models and the multi-pollutants models, PM2.5 and its chemical components inversely correlated with sperm motility in a relatively early window (from week 10 to week 11 before semen collection) which was identified to be more sensitive to air pollution.
Feng et al. (Tue,) studied this question.