Geographical variation in relative risks associated with heat: Update of Spain's Heat Wave Prevention Plan

A decade after the implementation of prevention plans designed to minimise the impact of high temperatures on health, some countries have decided to update these plans in order to improve the weakness detected in these ten years of operation. In the case of Spain, this update has fundamentally consisted of changing the so-called "threshold" or "trigger" temperatures used to activate the plan, by switching from temperature values based on climatological criteria to others obtained by epidemiological studies conducted on a provincial scale. This study reports the results of these "trigger" temperatures for each of Spain's 52 provincial capitals, as well as the impact of heat on mortality by reference to the relative risks (RRs) and attributable risks (ARs) calculated for natural as well as circulatory and respiratory causes. The results obtained for threshold temperatures and RRs show a more uniform behaviour pattern than those obtained using temperature values based on climatological criteria; plus a clear decrease in RRs of heat-associated mortality due to the three causes considered, at both a provincial and regional level as well as for Spain as a whole. The updating of prevention plans is regarded as crucial for optimising the operation of these plans in terms of reducing the effect of high temperatures on population health.