ABSTRACT
Extreme heat, exacerbated by the urban heat island (UHI) effect, is a leading cause of weather-related mortality in the United States and many other countries. Vulnerability to heat stress and patterns of heat-related morbidity and mortality are highly differentiated by age group and socio-economic status. Lower income populations often live in more built-up areas under more crowded conditions, and have less access to air conditioning or health services, making heat stress in urban areas a significant environmental justice issue. Current patterns of heat stress as a result of extreme heat events and the UHI effect are spatially varied at the city level, and can be shown to affect lower income populations and older age groups disproportionately. This chapter summarizes the literature on urban heat stress and associated morbidity and mortality, addresses aspects of urban ecology and the extent of built areas that promote UHI formation, and then addresses the social and political dimensions of exposure to heat stress. The chapter's concluding section addresses modifications to the urban environment and population's adaptive capacity through short-term response actions and long-term adaptation strategies that could help to reduce heat stress. We conclude that the inadequate appreciation of spatially differentiated factors contributing to extreme heat vulnerability limits the understanding of health risks and reduces the ability to prevent adverse heat health outcomes.
