| Previous research indicates a distinct seasonal pattern in mortality rates. Increases are prominent during the northern-hemispheric cold season. These patterns are seen in overall mortality, diabetes mellitus, circulatory, digestive, and respiratory diseases. A principal component analysis indicates that departure from normal temperature, minimum, maximum, and average daily temperature, and dew-point temperature are the primary atmospheric variables that influence mortality patterns. ANOVA and Kruskal-Wallis tests support findings of principal component analysis. Although a day-to-day relationship between mortality rates and atmospheric variables was noted in several instances, results suggest that the influence of the primary atmospheric variables on mortality rates is greatest when a three to five-day lag time is in place. Furthermore, results indicate that the combination of these variables in conjunction with frontal passage is linked to seasonal increases in mortality. A combination of atmospheric variables that influence mortality rates has been identified, however, their exact influence is still unclear. |
