Heat-health warning systems: Warning protocol definition and communication aspects

Heat-health action plans (HHAPs) aim at minimizing the negative impact of heat on human health. They follow a comprehensive approach that combines short-, medium- and long-term health prevention activities. Heat-health warning systems (HHWSs) constitute an integral part of HHAPs, providing alerts that target the initiation of autonomous (e.g. reduced physical activity) and coordinated (e.g. operation of cooling centers) intervention measures for health protection. The implementation of national and regional HHWS in Europe, but also worldwide, has proven to be successful in reducing heat-related mortality. Yet, further advancements, especially with respect to the warning protocol definition and the communication of warnings, are necessary to comprehensively characterize and deal with heat and its impact on human health. The current work provides insights in relation to these issues based on a prototype HHWS developed in the framework of the HEAT-ALARM research project. Employing Greece as a test bed, the HEAT-ALARM HHWS is operated under a pilot mode during the warm period (April-October) of 2024. The system provides human-biometeorological-based warnings along with recommendations for a health protective behavior for the next three days in 72 regional units (RUs) of the country and for six population subsets (men and women adults and seniors, as well as men and women working outdoors), based on: (i) the association of the forecasted daily maximum mPET (modified physiologically equivalent temperature) and relative mortality risk, accounting for short-term acclimatization effects, and (ii) the forecasted nighttime temperatures, accounting for urban effects in those RUs encompassing the cities of Athens and Thessaloniki, which together accommodate almost one fourth of the total Greece population. Additional risk factors, such as the duration of mPET-based heat stress exposure, are provided as supplementary information, while the choice of the targeted populations aims at accounting for sex and age equity in heat prevention planning, as well as for the increased sensitivity of outdoor workforce to thermo-physiological heat stress. The meteorological data used in the above warning protocol are derived from high resolution (≤ 2 km) weather forecasting models at population-weighted spatial scales to better reflect the thermal environment experienced by the people in each RU. When it is necessary, all heat-health warning-related information is communicated directly to various stakeholders (e.g. Hellenic Red Cross) via automated e-mails, as well as internally with operational forecasters of the METEO Unit at the National Observatory of Athens (NOA), which operates a dedicated web page (www.meteo.gr) for issuing operational weather forecasts. The NOA/METEO website is visited by more than 350,000 visitors per day, ensuring thus the effective dissemination of the HEAT-ALARM heat-health warnings to end-users (e.g. construction workers) and/or their advocates (e.g. care facilities for the elderly), when needed.