抄録
Based upon the writers previous studies on the concentration of deaths/in winter in Japan and West European countries on the one hand, and on the other, the considerable moderation of seasonal variation in mortality or rather “deseasonalization” of deaths in the Scandinavian countries and the United States, the writers/attempt in this paper to analyze quantitatively the difference between these two types of seasonal variation in mortality and specifically the geographical difference in relationship between mortality (stroke and infant) and temperature in the three cities of London, Tôkyô and New York, and they sincerely want to build up one of the groundworks necessary for long-term biometeorological forecast. For such statistical analysis, covariance in two-way layout is used.
Covariance analysis indicates that there is no significant difference among the three cities between the regression of mortality (stroke and infant) on temperature in spring and that in autumn in the 1960's, so the changes per 10°C in the death rate are calculated by the average regression coeffcient. Mortality is inversely related to temperature, and the increase or decrease per 10°C in the death rate for stroke turns out to be larger than that for infant mortality in the three cities. In both Tôkyô and London, the rise of the death rate for stroke in fall is considerably large, or 28.5% and 39.3%, respectively, in contrast to only 8.7% in New York over three and four times larger, respectively.
As for infants, the mortality rate decreases or increases very slightly (not more than 1.5%) in New York along with the ups and downs of temperature. The corresponding rate of increase or decrease is about 8% in London. In Tôkyô, however, the infant death rate declines by about 14% with temperature up 10°C and goes up by as much as 20% with a similar drop of temperature.
The changes in the death rate with the variation of temperature turn out to be the smallest in New York among the three metropolises. All this clearly indicates that central heating, widely adopted in American cities, has brought about favorable bearings upon mortality, especially that of infants who can live entirely in the artificial climate. It is also to be noted that mortality from stroke undergoes much larger changes with the ups and downs of temperature in London than in Tôkyô, and vice versa in the case of infant mortality.
