 The study aimed at developing a standardized definition for heat waves to estimate their impact on mortality in Europe during summers 1990 to 2004 and 2003 separately. Heat waves were defined based on maximum and minimum temperature, intensity, duration, and timing during summer. The effect was estimated as the percent increase in daily mortality during heatwave days compared to non-heatwave days in people over 65 years. Results showed great geographical heterogeneity among cities with an increase in mortality ranging from plus 7.6% in Munich to plus 33.6% in Milan. The impact was up to three times greater during episodes of long duration and high intensity. Pooled results showed a greater effect in Mediterranean, plus 21.8%, the North Continental, plus 12.4% cities with the highest impact observed for respiratory diseases and among women aged 75 to 84 years. In 2003, the highest impact was observed in cities where heatwave episodes were characterized by unusual meteorological conditions. The study concludes that prevention programs should specifically target the elderly, women, and those suffering from chronic respiratory disorders to reduce the impact on mortality. This article was authored by Basanti Laliji, Kovatsari, Atkinson Richard, and others. We are article.tv, links in the description below.