Environmznt Intonational, Vol. 17, pp. 397-403, 1991 0160-4120/91 $3.00+ .00 Printed in the U.S.A. All righu reserved. Copyright © 1991 Pergamon Pressplc MULTIVARIATE ANALYSIS OF THE RELATION- SHIP BETWEEN METEOROLOGICAL AND POLLUTANT VARIABLES AND THE NUMBER OF HOSPITAL ADMISSIONS DUE TO CARDIO- RESPIRATORY DISEASES Nieves Dlaz-Caneja and Isabel Guti~rrez Department of Medical Physics, Faculty of Medicine, University of Cantabda, Cardenai Herrera Oria s/n, 39011 Santander, Spain Antonio Martinez Data Processing Section, National Institute of Agrarian Research,Apdo. 8111, 28080 Madrid. Spain Pedro Matorras Department of Intamai Medicine, National Hospital "Marqu6s de Vaidecilla', 39008 Santander, Spain Eugenio Villar Department of Fundamental Physics, Faculty of Sciences, University of Cantabria, Avda. de los Castros s/n, 39005 Santander, Spain El 88-I06 (Received5 August 2988; accepted 15 December 1990) This paper studies the influence of meteorological and air pollutant parameters on the number of hospital admissions due to acute exacerbation in chronic obstructive pulmonary disease (COPD) and heart failure (HF), in the city of Santander (Spain), over a 4-y period. In the multiple linear regression study performed, the variable, which overall shows the strongest correlation with the number of admissions for the two diseases, is the concentration of suspended particulate matter (SPM). Of the meteorological variables studied, the best correlations are with pressure gradient and temperatures: pressure gradient and maximum temperature for admissions due to COPD, and pressure gradient and mean temperature for HF. This behaviour shows seasonal variations with the highest multiple correlation coefficients corresponding to autumn. High pressures, both maximum and minimum, significantly increase the number of admissions for both diseases. Of the pollutant variables, the SPM concentrations reveal a greater relationship with admissions for both diseases than the SO= concentration does. It is worth noting that the influence of pollution on the number of admissions is produced at values much lower than those recommended as limits by legislation. INTRODUCTION There is, at the present time, considerable interest in studies whose aim is to determine the influence of climate, weather changes, and atmospheric pollution on health. Of the atmospheric factors, one which has a strong influence on the human organism is environ- mental pollution which acts mainly on the respiratory system. While most authors accept that these factors 397