According to a study published in The Lancet, acute exposure to heat and cold can increase the risk of mortality from multiple causes of death.
In 2019, in all countries for which data were available, the average mortality attributable to cold exceeded the mortality attributable to heat. The effects of cold were most pronounced in China and New Zealand, while the effects of heat were more pronounced in China and Brazil. Globally, an estimated 1.69 million deaths were attributable to extreme temperatures .
17 causes of death
The researchers found that 17 causes of death met the inclusion criteria. J-shaped relationships with daily temperature were observed for ischemic heart disease, stroke, cardiomyopathy and myocarditis, hypertensive heart disease, diabetes, chronic kidney disease, lower respiratory tract infection, and chronic obstructive pulmonary disease; the risk of external causes, including homicide, suicide, drowning, and unintentional injury, increased monotonically with temperature .
Estimates of non-optimal temperatures ranged from 7.98 to 35.1 deaths per 100,000 in Brazil and China, respectively, with population-attributable fractions of 1.2 and 4.7 percent, respectively.
Katrin G. Burkart of the University of Washington in Seattle and her colleagues linked deaths to daily temperature estimates, modeled cause-specific relative risks for individual causes of death, and calculated the burden attributable to total temperature and specific to the cause. The cause-specific relative risks were then applied to all locations globally .