Heat, heatwaves and cardiorespiratory hospital admissions in Helsinki, Finland

Background There is a lack of knowledge concerning the effects of heat on morbidity in Northern Europe. Therefore, this study aimed to evaluate the relationships of daily summer-time temperature and heatwaves with cardiorespiratory hospital admissions in Helsinki, Finland. Methods Time-series models adjusted for potential confounders such as air pollution were used to investigate the associations of daily temperature and heatwaves with cause-specific cardiorespiratory hospital admissions, during the summer months of 2000-2017. Daily number of hospitalizations was obtained from the national hospital discharge register, weather information from the Finnish meteorological institute. Results Heatwave-days were associated with an increased risk of pneumonia (RR: 1.17, 95%CI: 1.04-1.31), any respiratory disease in some age groups, and myocardial infarction (RR: 1.54, 95% CI: 1.12-2.12) among person 65-74 years of age. In addition, high effect estimates were observed for many types of cardiorespiratory diseases in association with heatwaves in some age-groups. In contrast, risk of arrhythmia was decreased during heatwaves (RR: 0.81, 95% CI: 0.70-0.93). Conclusions We found no associations and even protective associations between daily mean temperature and cardiorespiratory hospital admissions. However, our results suggest that heatwaves are a serious health threat affecting the morbidity even in the Northern climate Key messages Heatwaves are associated with increased risk of cardio-respiratory hospital admissions. There is a need to adapt to climate change in the public health sector also in Northern Europe to protect vulnerable population groups.