Exposure to residential green space and semen quality among Chinese men

Background: Residential greenness has been linked to various health benefits, but evidence on its association with sperm quality remains limited.

Methods: We enrolled 28,089 adult men from an infertility clinic in Hubei, China, from 2014 to 2020. Residential greenness was estimated using the Normalized Vegetation Index (NDVI) from satellite imagery, averaged within buffers of 250 m, 500 m and 1000 m around each participant's residential address. We employed multivariate linear regression analysis to evaluate the association between NDVI exposure and semen quality, while controlling for individual characteristics and semen collection season. Additionally, we performed subgroup analyses to investigate potential variations in the association based on individual characteristics.

Results: An interquartile range increase of 0.243 in NDVI within the 1000 m buffer was associated with increases of 1.68 % (95 % CI: 0.31 %, 3.06 %) in sperm concentration, 0.43 % (95 % CI: 0.08 %, 0.79 %) in progressive motility, and 0.50 % (95 % CI: 0.14 %, 0.87 %) in total motility. These associations were consistent across different buffer sizes. The associations were more pronounced during the 70-90 lag days prior to semen collection (spermatogenesis stage) and among men aged ≥ 40 years or those with lower education levels.

Conclusions: Our study demonstrated that exposure to residential greenness may act as an innovative protective factor for semen quality.