Heat-related excess mortality in Brazilian urban areas: regional, demographic and social disparities

Climate Change has increased population exposure to more frequent, more intense, and longer heat waves (HWs) worldwide. South America and particularly Brazil is highly vulnerable to rising temperatures, with limited adaptation resources and a growing and aging urban population. However still lacks research on the direct and indirect impacts of extreme heat on health in these regions, in particular on the role of social and demographic factors, as well as regional disparities in heat-related mortality. This work presents a comprehensive analysis of the occurrence of HW in the 14 most populous metropolitan regions (MRs) in Brazil, comprising circa 35% of the country's population, based on the Excess Heat Factor index. The impact of HWs on mortality was accessed employing the ratio between observed and expected deaths (O/E), which reveals a burden of 48,075 excess heat-related excess deaths over the 2000–2018 period, in line with the recent and significant increase observed in the annual number of days under extreme heat. Diseases of the circulatory and respiratory systems and neoplasms are the dominant causes of death (COD), although other COD little explored in the literature have also presented large O/E values in some MRs, such as diseases of the skin, nervous and genitourinary system, and mental and behavioral disorders. In addition, the vulnerability population profile was investigated considering the splits in terms of gender, age, race, and educational level subgroups. Overall, females, older, low-educational level, and black/brown are the most sensitive groups in most MRs, with significantly larger O/E values. Nonetheless, significant regional disparities were observed, mainly due to North-South socio-economic inequalities existing in Brazil, and differences in health indicators between these regions, such as life expectancy. Our findings are expected to guide the implementation of public mitigation and adaptation strategies in some of the most populated regions of South America.

This work was supported by FIOCRUZ [grant VPPCB-003-FIO-19] and FAPERJ [grant E26/202.714/2019]. D.M.S. was supported by FIOCRUZ [grant VPPCB-003-FIO-19].