Long-Term Exposure to Ambient Air Pollution and Prevalence of Infertility.

Infertility affects 15% of reproductive-age people worldwide and continues to impose a significant health burden. Several recent studies have linked ambient air pollution to infertility, but the evidence remains limited and inconclusive. We obtained global data on prevalence of infertility for 534 global spatial units and high-resolution air pollutants from the Global Burden of Disease (GBD) study during 2005-2020. Using a difference-in-differences approach, we estimated that each 10 μg/m3 increase of exposure to fine particulate matter (PM2.5) and ozone (O3) was significantly associated with a 28% and 17% higher risk of infertility prevalence, respectively, while an inverted U-shaped association was observed for nitrogen dioxide (NO2). These associations were generally stronger for secondary infertility compared with those for primary infertility. We identified stronger associations of exposure to both PM2.5 and O3 with infertility in the middle latitude and low GDP per capita regions. If the exposure to PM2.5, O3, and NO2 was decreased to levels recommended by the 2021 WHO AQGs, 17.4%, 24.2%, and 5.0% of the infertility prevalence would be avoided, respectively. Our findings strengthen the evidence that long-term exposure to ambient air pollution elevates the risk of infertility, highlighting the importance and urgency of reducing exposure to air pollution in improving human reproductive health.