BackgroundCritical windows for exposure to chemical components of particulate matter (PM <2.5 μm in diameter [PM2.5]) associated with the human semen quality decline remain unclear. ObjectivesTo address this gap, we developed a new analytical framework by integrating a Linear Mixed Model (LMM) with subject- and center-specific intercepts and a Distributed Lag Model (DLM) to fully account for correlations between finely vulnerable exposure windows based on complete profile of the spermatogenesis cycle. MethodsWe constructed a multicenter cohort involving 33,234 sperm donors with 78,952 semen samples covering 6 representative regions across China from 2014 to 2020 to investigate the week-scale critical windows for the exposure. Daily exposure to PM2.5 chemical components of donors was derived from grid data based on 1-km spatial resolution surface measurements. ResultsDecreased sperm count was significantly associated with NO3− and SO42− at 9–10 weeks (e.g., β: -0.05 %, 95%CI: [−0.10 %, −0.00 %] at the 9th week) and 0–2 weeks (e.g., β: -0.66 %, 95%CI: [−1.24 %, −0.07 %] at the 1st week), respectively. Critical windows of progressive motility decline were 0–10 weeks for BC (e.g., β: -0.07 %, 95%CI: [−0.11 %, −0.03 %] at the 5th week), Cl− at 1–4 weeks (e.g., β: -2.21 %, 95%CI: [−3.77 %, −0.66 %] at the 2nd week), 0–6 weeks and 9–10 weeks for NO3− (e.g., β: -0.05 %, 95%CI: [−0.09 %, −0.01 %] at the 4th week), 1–3 weeks and the 8th week for NH4+ (e.g., β: -0.06 %, 95%CI: [−0.11 %, −0.01 %] at the 2nd week). Total motility is significantly negatively associated with BC at entire windows, Cl− at 0–3 weeks, the 5th week and 9–10 weeks. ConclusionsThere are week-scale vulnerable windows of exposure to PM2.5 chemical components for human semen quality. This highlights the need for more targeted pollution control strategies addressing PM2.5 and its chemical components.
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