Does Air Pollution Impact on Semen Parameters? Findings from a Real-Life, Cross-Sectional Study in Italian Infertile Men

Purpose: In industrialized countries, air pollutants levels have been monitored closely for environmental and research issues. Using Italian data, we aimed to investigate the association between air pollutants levels and semen parameters in a cohort of non-Finnish white-European men presenting for couple's infertility. Materials and methods: Complete demographic and laboratory data from 1,152 infertile men consecutively assessed between January 2015 and January 2018 were analyzed. Semen analyses were based on the 2010 World Health Organization reference criteria. Health-significant comorbidities were scored with the Charlson Comorbidity Index (CCI). We analyzed the annual average level of the three main markers of air pollution (Pm10, Pm2.5, and NO2) between 2014 and 2018. Descriptive statistics, linear and logistic regression analyses tested the association between air pollutants levels and semen parameters. Results: Of 1,152 men, 87 (7.55%) had normal sperm parameters at first semen analysis. Of 1,065 patients with abnormal semen analyses, 237 (22.25%), 324 (30.42%), and 287 (26.95%) patients presented 1, 2 or 3 abnormalities, respectively, and 217 (20.38%) were azoospermic. At linear regression analysis, Pm10, Pm2.5, and NO2 were negatively associated with sperm morphology (Pm10: β=-0.5288 µg/m3, p=0.001; Pm2.5: β=-0.5240 µg/m3, p=0.019; NO2: β=-0.4396 µg/m3, p<0.0001). Furthermore, the adjusted odds of normal sperm morphology <4% were 1.06 (95% confidence interval [CI], 1.03-1.09; p=0.007) for Pm10, 1.07 (95% CI, 1.03-1.11; p=0.007) for Pm 2.5, and 1.03 (95% CI, 1.02-1.05; p=0.001) for NO2, respectively. Conclusions: In a large homogenous cohort of infertile men, Pm10, Pm 2.5, and NO2 levels were negatively associated with sperm morphology. Conversely, no clear association was observed with other macroscopic sperm parameters.