Epidemiologic study of mortality during the summer of 2003 in Italy

The heat-wave which interested Europe from May to September 2003 represented an extreme event even in Italy for the recorded thermic levels, persistence of high temperature values over the standard and long duration (lasting) of drought. Starting from the last half part of May until the end of the summer, the anticyclone of the Azores was firmly blocked on the medium-European regions, driving the meteorological conditions (high temperature and absence of precipitations) on the western and southern Europe. The anticyclone intercepted and deviated the atmospheric western flows and it prevented to alleviate those extreme uneasiness conditions perceived from people. The positive thermic anomaly involved all Italian regions, from Alps to Islands. It is widely recognized that extreme climatic conditions during the summer months can constitute a major public health threat. Persons living in cities have an elevated risk of death when the temperature (and humidity) are high, compared with those living in suburban and rural areas (“urban heat island effect”). Studies on heatwave related mortality have further demonstrated that the greatest increases in mortality occur in the elderly. Communal offices, which maintain vital statistics, were asked for the number of deaths among resident people, registered during the period June 1-August 31, 2003 and during the same period during 2002, for each of the 21 capitals of the Italian regions. Within the framework of a collaboration with the Italian Central Office for Agriecology (UCEA), meteorological data ( minimum / maximum temperature and humidity) were obtained for the observed periods 2002 and 2003; this allowed to calculate discomfort indexes, such as the Humidex. Compared with 2002 , during the three summer months (1 June-31 August 2003) there was an overall increase in mortality of 3,134 (from 20,564 in 2002 to 23,698 in 2003). The greatest increase regarded elderly people : 2876 deaths (92%) occurred among people aged 75 years and older. The increase in mortality was greatest in the cities belonging to the Northwest of the country (31.5%), followed by the South (17.8%), the Northeast (16.4%) and the Centre (16.3%) . With respect to each city, the greatest increase was observed in Turin (45%) - where the deaths more than doubled during the first fifteen days of August- , Milan (30.6%) and Genoa (22.2%) . It is noteworthy that some cities in the South experienced their highest increase in mortality during the last period of August: in Bari the overall excess mortality was 33.8%, but in the last part of August it reached 137%. In these cities, the relationship between mortality and climatic indexes (t. max, Humidex) was investigated and a clear correlation was observed.