Ambient fine particulate matter constituents and semen quality among adult men in China

Exposure to ambient fine particulate matter (PM2.5) was associated with decreased semen quality, but the relationship between PM2.5 constituents and semen quality was unclear. We recruited 27,824 adult men attending an infertility clinic in Wuhan, China, between 2014 and 2020. We used a four-dimensional spatiotemporal deep forest model to estimate concentrations of PM2.5 mass and its chemical constituents, including organic matter (OM), black carbon (BC), sulfate (SO42- ), nitrate (NO3-), ammonium (NH4+), and chloride (Cl-). We employed linear regression models to estimate the association between PM2.5 mass and its constituents with various sperm parameters. Exposure to PM2.5 was associated with a reduction in sperm quality, with a percent change of - 5.69% (95% confidence interval [CI]: -8.53%, -2.85%) for sperm density, - 15.09% (95% CI: -22.24%, -7.94%) for sperm total count, - 1.63% (95% CI: -2.36%, -0.91%) for sperm progressive motility, and - 2.30% (95% CI: -3.04%, -1.55%) for sperm total motility. Among specific constituents, exposure to OM, BC, Cl-, or NO3- was associated with a reduction in these four semen quality parameters. The association was more pronounced among older men or individuals with lower levels of education. Our findings suggest that PM2.5