Heat exhaustion, domestic heat exposure, and socioeconomic disparities among older adults in Germany

Background

Due to age-related physiological changes, older adults are particularly vulnerable to heatwaves. While cool indoor temperatures can mitigate adverse health effects of extreme outdoor heat, access to such cooling remains unevenly distributed across populations. This study aimed to assess the mediating effect of domestic heat exposure on the relationship between socioeconomic position and heat exhaustion among older adults.

Methods

10,000 participants from the DigiHero cohort were invited in August 2024 to take part in an online survey. The analysis sample included 1,457 persons aged 65+ years, selected from 5,026 respondents overall. Domestic heat exposure was assessed through self-reported indoor temperatures during the day and at night, and the availability of cooler rooms at night. Heat exhaustion was measured using self-reported symptoms. Income and education were used as indicators for socioeconomic position. Structural equation modeling was applied to assess the total impact of socioeconomic position (education/income) on heat exhaustion and the portion of this effect mediated through domestic heat exposure. In addition, analyses were stratified by sex/gender and degree of urbanization.

Results

Participants were on average 72.8 years old, 54% were female, 50% had a high level of education, and 70% were not exposed to domestic heat. Lower income and education were associated with more frequent heat exhaustion symptoms. Lower income was associated with higher domestic heat exposure, which mediated the income-heat exhaustion relationship (total effect β = -0.09 (-0.14, -0.03); indirect effect β = -0.01 (-0.02, -0.003)). These effects appeared only in women and were stronger in urban settings.

Conclusions

Lower income is associated with more frequent heat exhaustion symptoms in older women, partially due to differential exposure to domestic heat.

Key messages

• Inequalities in the health consequences of heat exposure among older adults in Germany exist.

• Domestic heat exposures contribute to these disparities, as indicated by mediation effects among women.