The results of the project showed that the health risks were almost wholly dominated by daily mean temperature, while the added effect of heat waves, temperature variability (ie, diurnal temperature range [DTR] and inter-day change in temperature), and compound hot and humid or high pollution events was limited to a reduced number of diseases. It was also found that the health risks varied widely depending on cause-specific disease and individual characteristics such as sex (women were at higher risk from heat), age (very young children and the elderly), or education (less educated). Moreover, the project also documented a temporal reduction in risk of mortality due to hot and cold temperatures in Spain and France, suggesting that climate warming in the last decades has been paralleled by a progressive adaptation of the Spanish and French populations to ambient temperatures.
Regarding the role of socioeconomic factors, the project found that the Spanish regions with higher heating prevalence were less vulnerable to cold-related mortality. However, the prevalence of heating in Spanish households showed large spatial disparities: the warmest regions in Spain (ie, in the south of the country), which are also the poorer, had the lowest prevalence of houses with central heating. Reducing this geographical inequality could save thousands of premature deaths from cold every year, particularly among the elderly with low socioeconomic level, and thus increase the overall life span. In the small-area studies performed in France, the spatial differences in vulnerability to heat were not explained by demographic/socioeconomic factors, but rather by the degree of urbanisation or overexposure to heat (Urban Heat Island) and air pollution. People living in cities were at a higher risk of dying from heat, although urban greening mitigated this risk in the city big cities like Paris. Moreover, by analysing the role of a wide range of relevant contextual factors in shaping the time trends in heat- and cold-related mortality risk, the project found that air conditioning and heating are effective societal adaptive measures to non-optimum ambient temperatures.
