Sperm quality and ambient air pollution exposure: A retrospective, cohort study in a Southern province of China

Abstract

BackgroundAbnormal semen quality is one of the common causes of infertility. The relationship between exposure to air pollutants and semen quality is unclear. ObjectivesTo evaluate the impact of ambient air pollutant exposures on semen quality. MethodsWe analyzed 3797 semen samples from Guangdong Human Sperm Bank between May 28, 2018 and March 31, 2019. The inverse distance weighted interpolation method was used to estimate the personal exposures to CO, SO2, NO2, O3, PM10 and PM2.5 during the entire period (0–90 lag days) and key periods (0–9, 10–14, 70–90 lag days) of sperm development. Linear mixed models were used to evaluate the exposure-response relationships between air pollutants and semen quality, including sperm concentration, sperm count and sperm motility, after adjusting for other covariates. The regression coefficients and 95% confidence intervals (CIs) associated with each interquartile range (IQR) increase in pollutant concentrations were estimated for each semen quality parameter. ResultsOverall, we observed a significant association of decreased sperm count with the exposure to PM10 (−0.2466; −0.4443, −0.0489) and PM2.5 (−0.2910; −0.5401, −0.0419). Among the sperm quality parameters assessed, sperm count was observed more frequently to be negatively associated with ambient air pollutants (CO, NO2, O3, PM10 and PM2.5), especially for the period during 10–14 lag days. In addition, motility decline was significantly associated with O3 in the late stage of sperm development. Sensitivity analyses for subgroup population yielded similar results. No significant association was found between all pollutants and sperm concentration (all P > 0.05). ConclusionsOur results indicate that ambient air pollutants exposures during sperm development may have an adverse effect on semen quality, especially for sperm count and motility. The findings emphasize the potential to improve semen quality by reducing ambient air pollutant exposures, and the importance of taking into account the critical period of sperm development when protective measures are implemented.