Air pollution and male infertility: A meta-umbrella study of evidence on semen quality

Growing epidemiological evidence links air pollution to male reproductive health through oxidative stress, endocrine disruption, and direct cellular damage. However, the magnitude and consistency of effects on semen quality parameters across different pollutant types and exposure durations remain uncertain.

We systematically searched PubMed, Web of Science, and Scopus through January 2025 for meta-analytic studies evaluating the impact of air pollution on semen parameters. Four eligible studies were assessed for methodological quality using AMSTAR 2. Random-effects meta-analyses yielded standardized mean differences (SMDs) for sperm concentration, count, total motility, progressive motility, and morphology.

We observed statistically significant negative associations between higher air pollution exposure and semen quality outcomes. Specifically, greater pollutant exposure was associated with lower total motility (SMD -0.24; 95% CI -0.48 to -0.01; P = .04), progressive motility (SMD -0.06; 95% CI -0.10 to -0.01; P < .001), and morphology (SMD -0.09; 95% CI -0.13 to -0.04; P < .001). Concentration was inversely related to pollution levels (SMD -0.14; 95% CI -0.21 to -0.06; P < .001), while sperm count showed a trend toward reduction but did not reach statistical significance (SMD -0.12; 95% CI -0.26 to 0.01; P = .06).

This meta-umbrella analysis confirms consistent, modest negative associations between ambient air pollution and key semen quality parameters, underscoring air pollution as a modifiable risk factor for male infertility. Future studies should define threshold exposures and evaluate protective interventions.