Environment/Climate Change
Housing Type Modifies the Association Between Ambient Temperature and Indoor Cardiac Arrest in a Large Japanese City Akihiko Narisada* Akihiko Narisada Narisada Narisada Narisada Aichi Prefectural University
Background: Climate change is increasing the frequency and intensity of heat exposure, raising concerns about heat-related cardiovascular events. Indoor heat exposure, influenced by housing characteristics and cooling behaviors, may be particularly important for severe outcomes such as cardiac arrest. The World Health Organization’s Housing and Health Guidelines emphasize maintaining safe indoor temperatures through adequate housing and appropriate air conditioner use. In Japan, however, housing conditions and air conditioner use differ between detached houses and apartment buildings. This study examined the association between ambient temperature and emergency ambulance transport for cardiac arrest occurring in living rooms, stratified by housing type, in a large Japanese city.
Methods: We analyzed ambulance transport records for out-of-hospital cardiac arrest occurring in living rooms of residential dwellings in Nagoya City, Japan (population ~2 million), between April 2016 and March 2022. A time-stratified case-crossover design was used to assess short-term associations between daily mean temperature and cardiac arrest risk. Temperature effects were modeled using distributed lag nonlinear models, with 15°C as the reference. Analyses were stratified by housing type: detached houses and apartment buildings.
Results: A total of 5,489 cardiac arrest cases were included (3,147 in detached houses and 2,342 in apartment buildings). No increased risk was observed at low temperatures in either housing type. At high temperatures, risk differed by housing type. No increase was observed in detached houses at 30°C (RR 1.01, 95% CI 0.73–1.41), whereas a significant increase was observed in apartment buildings (RR 1.45, 95% CI 1.01–2.08).
Conclusions: In the context of climate change and increasing indoor heat exposure, residents of apartment buildings showed elevated risk of heat-related cardiac arrest occurring indoors, while no such increase was observed in detached houses. Promoting appropriate air conditioner use in apartment buildings during hot periods may be critical for preventing heat-related cardiac arrest.