Mapping Estimated Heat-Related Mortality In London Due To Population Age, Urban Heat Island, And Dwelling Characteristics

Abstract

Introduction Mortality during hot weather is predicted to become more significant in the UK due to changes in the climate. We investigated the spatial variation in heat-related mortality risks across London due to population age, urban heat island (UHI) and building characteristics. Methods Dynamic building physics models were run for 126 different age and built form variants of buildings statistically representative of the London housing stock, outputting average maximum daily internal temperatures for a hot summer period in 2006. Internal and modelled UHI temperature estimates for the same period in London were mapped to individual dwellings in Geographic Information System (GIS) software, and deviations of building-specific indoor and outdoor temperatures from the London-average were calculated and summarised at ward level. Office of National Statistics age-specific absolute mortality data and the above-calculated UHI and indoor temperature anomalies were then used to estimate spatial variation in mortality according to an age-specific relative risk function for heat in London. Results There was appreciable variation in indoor temperatures under the modelled climate, with a mean maximum range of 2.5°C. Modelled results indicate that the largest mortality risks may lie in outer London, as the elderly population is larger there than in Central London. Top-floor flats in multiple occupancy buildings and bungalows were found to be the most at-risk dwelling types. Limitations in building stock information and occupancy scenario assumptions mean that some buildings may be worse than modelled. Conclusions These results indicate that UHI and indoor temperatures may cause an appreciable spatial variation in the risks from heat-related mortality, but that the driving factor remains population age. Further work is required to explore the risks for individuals living in extreme heat-poor housing conditions or for those unable to take action to cool the indoor environment.