How is excess mortality due to heat calculated in Portugal?

During heat waves, when thermometers exceed 40°C, deaths may increase, although heat may not appear as a direct cause on death certificates. When the number of deaths rises above the usual, epidemiologists can identify the statistical signature left by high temperatures. The ÍCARO surveillance system seeks precisely to answer this question, measuring the risk for the Portuguese population. The starting point is not how many people officially died because of the heat, but rather how many deaths occurred above the expected number for that period. The system is coordinated by the National Health Institute Dr. Ricardo Jorge.