GES map heat stress - state 2018

Coverage map of the Health Effects Screening score (GES) of heat stress in Flanders. The indicator is based on the number of heat wave days (°C.day) in Flanders in the year 2018, modelled according to the methodology developed by VITO and used by the Flemish Environment Agency (2018). The indicator heat wave degree day (HGD) indicates where and by how many degrees Celsius the threshold values for minimum and maximum temperatures (respectively 18.2°C and 29.6°C), indicated by the FPS Public Health, are exceeded. For each location, the number of heat wave days is added up for all days of the year 2018. For the creation of the GES card, we use the HGD card of 2018, a recent exceptionally warm year. It has been opted to work with the map for an extreme year instead of an annual average map, because the health problems mainly occur during these types of summers, and in this way the potential problem locations are well identified and not underestimated. The GES classes were defined in this way: GES 2 = 0 - 20 (°C.day) = "reasonable"; GES 3 = 20 - 30 (°C.day) = "fairly moderate"; GES 4 = 30 - 40 (°C.day) = "moderate"; GES 5 = 40 - 60 (°C.day) = "very moderate"; GES 6 = 60 - 80 (°C.day) ="insufficient"; GES 7 = 80-100 (°C.day) = "well insufficient"; GES 8 > 100 (°C.day) = "very insufficient". GES 6 corresponds to at least 60 heat wave days, a value that occurred in Antwerp in the year 2003 and which is known to have suffered many casualties due to heat stress. However, a lower number of heat wave days also has negative effects on health. The map can be used to detect potential problem areas for heat stress in Flanders. In addition to air temperature, however, radiation load (both short-wave and long-wave), humidity and wind speed are also important factors in determining heat stress and human thermal comfort. The modelling does not take this into account. Locally, the actual heat stress experienced can therefore be higher (for example, due to local radiation from, for example, concrete or asphalt pavement) or lower (for example, because of shade from trees).