Association between urban density, built environment quality, and health: a multi-source study in Doha, Qatar.

Introduction: Rapid urbanization in hot-arid, car-dependent cities challenges the widely accepted assumption that urban density inherently promotes public health. While higher residential density is often associated with increased physical activity and improved health outcomes in Western contexts, its effects in cities such as Doha, Qatar, remain insufficiently understood. This study examines the relationship between residential density, environmental quality, and health outcomes in Doha's rapidly developing urban environment. Methods: A cross-sectional study was conducted using a mixed-methods approach that triangulated self-reported health and quality-of-life data collected through the SF-36 survey (N = 301), clinical records on non-communicable disease (NCD) prevalence obtained from Primary Health Care Corporations, and geospatial analyses of land use patterns and urban infrastructure across three residential zones in Doha. Associations between residential density, environmental conditions, and health indicators were examined. Results: Residential density was found to be differentially associated with health outcomes. Higher-density environments were associated with improved mental health and functional well-being; however, they were also associated with higher prevalence of non-communicable diseases and increased body mass index. These patterns appear to be influenced by contextual factors including inadequate pedestrian infrastructure, exposure to extreme heat, and limited climate-responsive urban design. The findings were particularly evident among vulnerable population groups engaged in necessity-driven walking. Discussion and conclusions: The results demonstrate that density alone is not a sufficient predictor of positive health outcomes in hot-arid urban environments. Environmental quality and the provision of climate-responsive infrastructure appear to play a more important role in shaping public health outcomes than density itself. The study highlights the need for urban planning and public health policies that move beyond densification strategies and prioritize walkability, thermal comfort, and high-quality urban environments to support NCD prevention and healthier lifestyles in rapidly developing cities.