Climate change exposures, chronic diseases and mental health in urban populations -- a threat to health security, particularly for the poor and disadvantaged.

Summary This report summarizes climate change trends globally and in selected urban areas. It analyses to what extent climate variables and climate change can influence chronic disease and mental health occurrence in populations in different places, with a particular focus on urban settings. The report also highlights gaps in the scientific evidence and provides recommendations for future research of WHO and other entities. Finally, it makes proposals for new research within the WHO urban health activities. The material used in this report is selective, and a full review of all the aspects of this topic would require a more substantial analysis. This was not possible with the limited scope of the project. Until now, the assessments of the global health impact of climate change have focused only on acute effects that can be approximately quantified. Malnutrition, diarrhoeal diseases and vector-borne diseases dominate such assessments, but no analysis to date has considered all potential health impacts of climate variability and climate change. It is possible that a number of the acute health problems associated with climate change could lead to long-lasting chronic conditions in affected individuals. Increasing heat exposure can also worsen the clinical condition of people with pre-existing chronic diseases and mental health problems. This would of course add to the burden of prevalent chronic disease problems in a population. The physiological reaction to increased heat exposure may also under certain conditions cause metabolic malfunction that would lead to chronic conditions. The international research recommendations in this field are relatively vague, but they do highlight the need to learn more about the specific health problems that are associated with direct heat exposure and the various indirect exposures that may occur with climate change. The identification of factors associated with vulnerability to health effects of climate change is also a priority. The health sector needs new decision-support tools and evaluations of health protection strategies in relation to climate change, including mitigation and adaptation strategies.