Impacts of Outdoor Air Pollution on Human Semen Quality: A Meta-Analysis and Systematic Review

Abstract

Introduction. Several studies have explored the association between outdoor air pollution and semen quality. However, the results were inconsistent. We performed the current meta-analysis to evaluate the role of outdoor air pollution in semen quality. Material and Methods. Databases including PubMed, Web of Science, and Embase were searched to identify relevant studies. Relative data in participants under higher exposure and lower exposure to air pollution were extracted. Pooled weighted mean differences (WMDs) with corresponding 95% confidence intervals (CIs) were utilized to assess the effects of outdoor air pollution on semen quality. In addition, trial sequential analyses (TSAs) were performed to obtain a more comprehensive assessment of analyses. Results. A total of 11 studies with 4562 males were enrolled in the current meta-analysis. Higher air pollution levels were associated with significant decreases in semen volume (WMD: -0.16, 95% CI: -0.27 to -0.05), sperm concentration (WMD: -5.52, 95% CI: -9.88 to -1.16), progressive motility (WMD: -6.23, 95% CI: -11.64 to -0.81), total motility (WMD: -7.65, 95% CI: -14.09 to -1.20), and normal sperm morphology rate (WMD: -3.71, 95% CI: -5.59 to -1.82). In addition, the DNA fragmentation index significantly increased (WMD: 4.11, 95% CI: 1.94 to 6.29). Conclusions. Air pollution is associated with decreased semen volume, sperm concentration, motility, and normal morphology rate.

Semen quality as a potential susceptibility indicator to SARS-CoV-2 insults in polluted areas

“…The male reproductive system is particularly sensitive to environmental pollutants and chronic exposure to high levels of PM10, PM2.5, and to individual air pollutants such as NO2 and sulfur dioxide (SO2) negatively impacts sperm count, motility, and testicular volume (Zhang et al 2020 ). The mechanisms of damage to spermatogenesis caused by environmental agents are still largely unknown, although the imbalance of oxygen radical species (ROS) and the resulting oxidative stress may represent the common denominator by which pollutants alter seminal parameters such as sperm count, motility, morphology, and especially the integrity of sperm DNA (Bosco et al 2018 ; Jurewicz et al 2018 ; Nowicka-Bauer and Nixon 2020 ).…”

Is there a relationship between serum vitamin D and semen parameters? A cross-sectional sample of the Iranian infertile men

“…These conflicts may be due to the dependence of sperm quality and count on other parameters such as the optimal levels of related enzymes, hormones, and antioxidants [36]. Moreover, differences in ethnicity [37], genetic variations [38], the concentration of air pollutants [39], and other confounders may be the source of contradictory results as compared to previous studies. Our findings also revealed that vitamin D was significantly associated with percentage of sperm total motility, which is in line with some previous reports [15,16] and inconsistent with others [18,26,32,40].…”

Nighttime environmental noise and semen quality: A single fertility center cohort study

“…We obtained district-average of PM 2.5 which is calculated based on the measurements at maximum 40 regulatory air pollution monitoring sites in Seoul during 2016–2018 from the National Institute of Environmental Research as described in previous studies [ 27 – 29 ]. Three-month average concentrations of district-level PM 2.5 before the date of semen test were used in the model because the positive association between air pollution and semen quality in previous studies was based on the exposures at least 90 days before semen sampling [ 30 ]. We adjusted for area-level of deprivation index to control the impact of neighborhood socioeconomic status.…”