Built environment characteristics and drowning mortality: a global satellite-based analysis of urbanisation, infrastructure, and water proximity

Drowning remains a major global public health challenge, yet how built environment characteristics shape population-level drowning risk remains poorly understood. This study linked satellite-derived built environment data to subnational drowning mortality estimates across 203 regions in 12 countries from 2006-2021. It found that built environment associations with drowning mortality are complex, non-linear, and shaped by development context. Urban extent was strongly protective, while built area near water showed protection overall but increased risk when combined with high population crowding. Almost all drowning mortality variance occurred between regions rather than within regions over time, indicating risk is predominantly determined by place-based characteristics. Income-stratified analyses revealed profound heterogeneity: crowding was protective in low- to middle-income settings, while near-water built area was protective mainly in middle-income settings. These findings highlight the importance of tailoring drowning prevention strategies to local built environment configurations and development contexts.