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

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., PM2.5, 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 PM2.5, PM10, 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.