The aim of this study is to evaluate the possible associations between daily hospital admissions for cardiovascular, respiratory and digestive diseases in Salamanca (Spain) and weather conditions during the winters of 1995–2005. An objective daily air mass classification was performed by means of statistical analysis of ground-level meteorological data. This afforded seven main circulation weather types (CWTs) for the cold period, and the frequency distributions of these types and their meteorological characteristics were analysed.
A summary of the main characteristics of the hospital admission series and their distribution over the 10 years studied, together with the frequency distributions of the different diseases classified by ages, the average number of the hospital admissions for each day of week, type of disease and sex, is given. In addition, a comparison between air mass classification and hospital admissions was made using an admission index (AI), for each disease. Significant increases in hospital admissions for the cardiovascular AI were evident 24–48 h after a day characterized by an anticyclonic air mass, 4–5 days after a day characterized by a westerly air mass and 6–7 days after an easterly flow. For the respiratory AI, an increase was observed 2–3 days after a cyclonic situation, 4 days after a northeasterly situation, while for days characterized by southwesterly air masses no delay was observed. These results indicate that the effects of weather conditions on hospital admissions tend to occur some days after exposure. Copyright © 2008 Royal Meteorological Society