How do economic levels, urbanization, and infrastructure investments influence inequality in urban green space exposure? Insights from Japanese municipalities

Urban green spaces (UGS) are vital for urban sustainability, but unequal exposure to UGS can lead to serious health inequalities. The long-term drivers of inequalities in personal exposure to UGS and the underlying mechanisms remain insufficiently understood. This study measures trends in inequality in UGS exposure in 710 Japanese municipalities over a 20-year period (2000–2020). The direct and indirect effects of economic status, urbanization, and infrastructure investments on inequalities in UGS exposure were analyzed using partial least squares structural equation modeling while considering the mediating roles of land use, demographic, and greening factors. This study found that the distributional inequality in UGS exposure in Japanese municipalities has increased significantly over the past two decades. Economic levels, urbanization, and infrastructure investments drive UGS exposure inequality directly and indirectly through greening and population density. While these relationships may vary by period and region, UGS and population density remain key predictors. Given Japan's challenges related to population decline and aging, cities need to focus on population dynamics and the distribution and size of UGS based on specific economic conditions and stages of urbanization to formulate effective strategies for sustainable development.