Ambient air pollution and male fecundity: A retrospective analysis of longitudinal data from a Chinese human sperm bank (2013-2018)

Abstract

Ambient air pollution has adverse effects on human health and reproduction. A number of studies have suggested a significant association between ambient air pollution and human fecundity, with most studies focusing on cross-sectional data from the general male population with single semen samples. We conducted a retrospective study in China using longitudinal analysis of repeated semen samples to investigate the association between environmental exposure parameters (e.g., PM_2.5, PM₁₀, SO₂, NO₂, CO, ground temperature, and relative humidity) and sperm quality parameters (e.g., semen volume, sperm concentration, forward motility concentration, and percentage of progressive rate) during different exposure windows (current day, 90-day preceding). Data from 686 males and 4841 semen samples collected between 2013 and 2018 at Sichuan Provincial Sperm Bank were included in a mixed-effects model analysis. The study population was young, healthy, and well-educated. The results indicate that 90-day average concentrations of PM_2.5, PM_10, and CO were negatively associated with sperm concentration and forward motility concentration, whereas 90-day average concentration of O₃ was positively associated with forward motility concentration. Between-subject variability played the dominant role in overall model variance. Our results suggest that chronic exposure to particulate matter and CO may interfere with spermatogenesis.

Keywords: Ambient air pollution; Male fecundity; Pollution exposure; Reproductive health; Sperm quality.