Modification of heat-related mortality in an elderly urban population by vegetation (urban green) and proximity to water (urban blue): Evidence from Lisbon, Portugal.

BACKGROUND: Urban populations are highly vulnerable to the adverse effects of heat, with heat-related mortality showing intra-urban variations that are likely due to differences in urban characteristics and socioeconomic status. OBJECTIVES: To investigate the influence of urban green and urban blue, i.e., urban vegetation and water bodies, on heat-related excess mortality in the elderly above 65 years in Lisbon, Portugal between 1998 and 2008. METHODS: We used remotely sensed data and geographic information to determine the amount of urban vegetation and the distance to water bodies (the Atlantic Ocean and the Tagus estuary). Poisson Generalized Additive Models were fitted, allowing for the interaction between equivalent temperature [Universal Thermal Climate Index (UTCI)] and quartiles of urban greenness [classified using the Normalized Differenced Vegetation Index (NDVI)] and proximity to water (≤ 4 km versus > 4 km), while adjusting for potential confounders. RESULTS: The association between mortality and a 1°C in UTCI above the 99th percentile (24.8°C) was stronger for areas in the lowest NDVI quartile (14.7% higher; 95% CI: 1.9, 17.5%) than areas in the highest quartile (3.0%; 95% CI: 2.0, 4.0%). In areas > 4km from water, a 1°C in UTCI above the 99th percentile was associated with a 7.1% increase in mortality (95% CI: 6.2, 8.1%), whereas in areas ≤ 4 km from water, the estimated increase in mortality was only 2.1% (95% CI: 1.2, 3.0%). CONCLUSIONS: Urban green and blue appeared to have a mitigating effect on heat-related mortality in the elderly population in Lisbon. Increasing the amount of vegetation may be a good strategy to counteract the adverse effects of heat in urban areas. Our findings also suggest potential benefits of urban blue that may be present several kilometers from a body of water

Bioclimatic design for informal settlements

In this paper, a review of the reasons hindering the use of bioclimatic design principles in informal settlements is attempted and the perspective of bioclimatic design in those contexts is discussed. Among the main candidate reasons is the habit of mind induced by the belief that informal settlements grow organically, so as to invariably end up being optimized for their functional tasks. Another reason lies in the very nature of bioclimatic design, which is based on integration, that can be perceived as too a “weak” guarantee of perspective features, not very suitable for competing with clear-cut and powerful strategies like active climatic control. A third reason is constituted by the technical challenges which are presently still posed by the environmental simulation of open and intermediate spaces, especially in hot climatic conditions. In this context, some promising research lines related to climatic control and passive cooling are identified in this text. Those approaches are likely to benefit from an integrated blend of practice and theory and may contribute to increase the attractiveness of bioclimatic principles for the rehabilitation of informal settlements