Burden of environmental heat and cold exposure and its attributable risk factors in 204 countries and territories (1990-2021).

Background: Environmental heat and cold exposure poses significant public health challenges worldwide. Understanding the global, regional, and national burden of disease, as well as sociodemographic and risk factor associations, is essential for targeted interventions.

Methods: This secondary data analysis utilized age-standardized incidence rates (ASIR), mortality rates (ASMR), and Disability-Adjusted Life Years (DALYs) rates from the Global Burden of Disease Study 2021 to assess the health impacts of environmental heat and cold exposure globally from 1990 to 2021. Regional and national variations, as well as age, sex, and Socio-demographic Index (SDI) patterns, were analyzed. Health workforce density data from WHO were incorporated to examine associations with temperature-attributable burden.

Results: In 2021, 3.4 million incident cases (ASIR: 45.1 per 100,000; 95% UI: 42.3-48.1) and 36,000 deaths (ASMR: 0.4 per 100,000; 95% UI: 0.3-0.5) were attributed to environmental heat and cold exposure worldwide, with 1.68 million DALYs (age-standardized rate: 20.4 per 100,000; 95% UI: 18.9-22.1). From 1990 to 2021, DALYs decreased by 53% (95% UI: 49-57%), highlighting global progress. However, disparities persist, with Central Asia and sub-Saharan Africa exhibiting the highest burden. Mongolia reported the highest national rates (ASIR: 366.4; ASMR: 5.2; DALY rate: 238.1 per 100,000). Men generally faced greater risks than women, particularly in older age groups. Cold exposure contributed 68% of total temperature-related DALYs, with opposing SDI gradients for heat (negative correlation) and cold (positive correlation) burden.

Conclusions: While global reductions in temperature-attributable burden demonstrate progress, significant regional and national disparities persist, particularly in low-SDI regions. Effective healthcare policies, health workforce strengthening, and targeted interventions are critical to reducing the persistent burden in vulnerable areas.