Overview
- Researchers analyzed fertility evaluations from nearly 400 men seen at seven assisted-reproduction centers across four peninsular zones in Spain between mid‑2024 and late‑2025.
- The north of the peninsula showed the best semen measures with a mean total mobile sperm count of about 94.35 million versus about 50.11 million in the center, and lower motility reduction in the north (23.9%) compared with the south (55.4%) and center (53.4%).
- Participants reported similar lifestyles and health factors across regions, so the team says the most plausible explanation is environmental exposure, naming air pollution and other contaminants as likely suspects without identifying specific agents.
- The study used clinic-based, observational data so it shows association not proof of cause; authors caution the sample is not population‑representative and cannot pinpoint which pollutants, if any, are responsible.
- Investigators warn that lower semen quality raises the chance of male infertility and difficulty conceiving and they call for expanded monitoring, broader research on industrial and plastic-derived chemicals, and firmer policies to cut contaminant exposure.