Exposure to Fine Particulate Matter Constituents and Human Semen Quality Decline: A Multicenter Study.

Exposure to fine particulate matter (PM < 2.5 μm in diameter [PM 2.5 ]) may accelerate human sperm quality decline, although research on this association is limited. Our objective was to investigate the relationship between exposure to the chemical constituents of PM 2.5 air pollution and decreased sperm quality and to further explore the exposure-response relationship. We conducted a multicenter population-based cohort study including 78,952 semen samples from 33,234 donors at 6 provincial human sperm banks (covering central, northern, southern, eastern, and southwestern parts of China) between 2014 and 2020. Daily exposure to PM 2.5 chemical composition was estimated using a deep learning model integrating a density ground-based measure network at a 1 km resolution. Linear mixed models with subject- and center-specific intercepts were used to quantify the harmful impacts of PM 2.5 constituents on semen quality and explore their exposure-response relationships. Per interquartile range (IQR) increase in PM 2.5 exposure levels during spermatogenesis was significantly associated with decreased sperm concentration, progressive motility, and total motility. For PM 2.5 constituents, per IQR increment in Cl - (β: -0.02, 95% CI: [-0.03, -0.00]) and NO 3 - (β: -0.05, 95% CI: [-0.08, -0.02]) exposure was negatively associated with sperm count, while NH 4 + (β: -0.03, 95% CI: [-0.06, -0.00]) was significantly linked to decreased progressive motility. These results suggest that exposure to PM 2.5 chemical constituents may adversely affect human sperm quality, highlighting the urgent need to reduce PM 2.5 exposure.