A number of studies of Swedish conditions have been carried out during the 2000s. Most studies have focused on Stockholm, and have found that high temperatures result in increases in both hospital admissions and mortality.
Temperatures particularly affect the health of people with underlying illnesses or other risk factors. Studies show that people with a history of conditions including cardiovascular disease, diseases of the respiratory organs and psychiatric diseases seem to have been affected more by high temperatures.
Studies from other countries have found that those who use certain types of medication will also be affected to a greater extent. This relates primarily to diuretics and psychiatric medication. Other medications that affect the body’s ability to regulate temperature are also suspected of increasing an individual’s vulnerability during a heatwave.
Those conditions and circumstances in which a reduced ability to deal with high temperatures has been demonstrated are most common among the elderly. Many initiatives have therefore been directed towards older people.
In Sweden, an increase in hospital admissions when temperatures rise, particularly as a consequence of respiratory diseases, has also been demonstrated. However, this area has been researched less as the number of deaths is often easier to study when it is not affected by factors such as access to care, which results in clear seasonal variations as well as weekly patterns.
Health effects during the 2018 heatwave
Although studies had previously demonstrated relatively dramatic health consequences linked to heatwaves, these consequences did not influence decision-makers until summer 2018.
The Public Health Agency of Sweden reported around 750 more deaths than normal during the heatwave that affected Sweden for five weeks in July and August 2018. Models have subsequently shown that between 600 and 745 of these can be attributed to the high temperatures.
The increase in mortality affected the whole country, but Stockholm was the worst hit area. The models used to estimate the increase showed that the rise in mortality for the rest of the country followed the patterns observed in previous summers, while mortality in the capital rose considerably more than the models predicted. No studies have investigated what the underlying causes behind such a large difference between Stockholm and the rest of Sweden might be.