Hot and cold weather based on the spatial synoptic classification and cause-specific mortality in Sweden: a time-stratified case-crossover study

Osvaldo Fonseca-Rodríguez,Erling Häggström Lundevaller,Scott C Sheridan,Barbara Schumann

doi:10.1007/s00484-020-01921-0

Osvaldo Fonseca-Rodríguez, Erling Häggström Lundevaller + Show 2 more

Open Access

https://doi.org/10.1007/s00484-020-01921-0

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Abstract

The spatial synoptic classification (SSC) is a holistic categorical assessment of the daily weather conditions at specific locations; it is a useful tool for assessing weather effects on health. In this study, we assessed (a) the effect of hot weather types and the duration of heat events on cardiovascular and respiratory mortality in summer and (b) the effect of cold weather types and the duration of cold events on cardiovascular and respiratory mortality in winter. A time-stratified case-crossover design combined with a distributed lag nonlinear model was carried out to investigate the association of weather types with cause-specific mortality in two southern (Skåne and Stockholm) and two northern (Jämtland and Västerbotten) locations in Sweden. During summer, in the southern locations, the Moist Tropical (MT) and Dry Tropical (DT) weather types increased cardiovascular and respiratory mortality at shorter lags; both hot weather types substantially increased respiratory mortality mainly in Skåne. The impact of heat events on mortality by cardiovascular and respiratory diseases was more important in the southern than in the northern locations at lag 0. The cumulative effect of MT, DT and heat events lagged over 14 days was particularly high for respiratory mortality in all locations except in Jämtland, though these did not show a clear effect on cardiovascular mortality. During winter, the dry polar and moist polar weather types and cold events showed a negligible effect on cardiovascular and respiratory mortality. This study provides valuable information about the relationship between hot oppressive weather types with cause-specific mortality; however, the cold weather types may not capture sufficiently effects on cause-specific mortality in this sub-Arctic region.

Highlights

The effect of low and high ambient temperature on all-cause and cause-specific mortality has been studied in different geographic areas across the world (Luan et al 2018; Rey et al.Electronic supplementary material The online version of this article contains supplementary material, which is available to authorized users.2007; Sheridan et al 2019; Urban et al 2019; Urban and Kysely 2018)
We have previously shown the association between all-cause mortality and oppressive hot (DT and moist tropical (MT)) and cold (DP and moist polar (MP)) weather during summer and winter, respectively, in southern and northern locations in Sweden (Fonseca-Rodríguez et al 2019)
The highest monthly mean mortality rate for cardiovascular diseases was observed in Jämtland, ranging from 42.0 per 100,000 inhabitants in July to 56.2 in January, while the lowest rate was observed in Stockholm (Supplementary Material, Fig. S2)

Summary

Introduction

High and low temperatures are associated with higher risk of all-cause mortality and mortality by cardiovascular and respiratory diseases due to different pathophysiological mechanisms (Anderson and Bell 2009; Gasparrini et al 2012; Rocklöv 2010). It has been demonstrated that ambient temperature and other variables like relative humidity represent important risk factors for cardiovascular and respiratory diseases (Davis et al 2016; Rocklöv and Forsberg 2010). There is an increasing interest on assessing the relationship between weather and human health due to the synergic effect produced by many environmental variables on

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