Winter classification of air masses and weather types for the forecasting of hospital admissions for myocardial infarction in Florence, Italy

Recently, interest in the impact of the weather and climate on human health has become an issue of much greater significance. The aim of this study was to evaluate the relationship between the risk of hospital admission for myocardial infarction and daily weather conditions, according to a synoptic climatological approach. Data for daily admissions for myocardial infarction were provided by the Administration of Careggi Hospital in Florence for the period 1998-2003. Hourly meteorological data was obtained from a weather station located in the main urban park of Florence and managed by the Institute of Biometeorology of the National Research Council. The analyses were concentrated on winter season, when the maximum peak of hospitalization for myocardial infarction occurred. A principal component analysis and a successive clustering technique was applied to identify typical air masses characteristics of the Florentine area. A multiyear comparison of MI admissions between air mass types was made by the calculation of a myocardial infarction admission index. Sequences of air mass types and their impact on hospitalizations were also investigated. Two antyciclonic air mass types (the continental anticyclonic and the anticyclonic mixed tropical maritime and continental) and the cyclonic one, were often associated with high mean daily admissions for myocardial infarction, especially when consecutive days with these air mass types occurred.