A Biometeorological Study in the Seasonal Variation of Mortality from Cerebral Haemorrhage, and Cerebral Thrombosis & Embolism

Abstract

The seasonal variation of mortality from cerebrovascular diseases (cerebral haemorrhage, thrombosis & embolism, and others) in Japan is observed geographically and bioclimatologically, and international comparisons are made in this paper. Findings are summarized as follows:
1). Mortality generally curves up to a peak in winter. In summer, it declines for haemorrhage but slightly increases for thrombosis & embolism, probably due to high humidity in this season.
2) This phenomenon appears more clearly in the central (warm)than in the northern (cold) and southern (subtropical) parts of the Japanese archipelago, suggestive of the limited adaptability to the meteorological environment of the old-aged affected by cerebrovascular diseases.
3) The summer maximum of mortality from cerebral thrombosis & embolism is somewhat higher in the urban than in the rural districts, but there is little difference between Kanto (East) and Kansai (West) in this country.
4) The death rate is generally going down for haemorrhage but up for thrombosis & embolism year by year. It is necessary to secure better heating in winter and better air conditioning (less humidity) in summer, especially for old people.