Thermal Comfort Conditions and Mortality in Brazil.

Area of Science:

• Environmental Health Sciences
• Climatology
• Epidemiology

Background:

• Conventional temperature metrics inadequately capture thermal stress.
• Thermal indices integrate meteorological factors for a comprehensive assessment of perceived temperature.
• Understanding thermal comfort's impact on health is crucial for public health policy.

Purpose of the Study:

• To estimate the association between thermal comfort conditions and mortality from respiratory and circulatory diseases in Brazil.
• To evaluate the performance of four distinct thermal indices: discomfort index (DI), net effective temperature (NET), humidex (H), and heat index (HI).

Main Methods:

• Analysis of a large dataset comprising 2,872,084 deaths in Brazil from 2003 to 2017.
• Examination of relative risk (RR) variations based on health outcomes, exposure lag, exposure percentile, and demographic groups (sex/age).
• Statistical modeling to assess the impact of DI, NET, H, and HI on all-cause mortality.

Main Results:

• Significant associations were found between thermal indices and mortality, varying by index, lag, and exposure level.
• High exposure (99th percentile) showed robust effects on all-cause mortality with shorter lags (3-10 days).
• Low exposure (1st percentile) also linked to increased all-cause mortality across most subgroups, particularly at lag 20.

Conclusions:

• Thermal indices provide a more accurate assessment of climate-related health risks than simple temperature.
• Findings highlight the need for public health interventions in Brazil to mitigate the impact of thermal stress.
• Policy development should incorporate these indices to address climate change's effects on mortality.