When daily high temperatures climb to 38 degrees Celsius or above, the share of heat illness cases occurring inside the home doubles compared with cooler days, according to a new government analysis — a finding that underscores the danger of staying indoors during extreme heat.
The National Disaster and Safety Research Institute under the Ministry of Interior and Safety released the findings Saturday after analyzing data from the Korea Disease Control and Prevention Agency (KDCA) and the Korea Meteorological Administration spanning 2011 to 2025. During extreme heat events — when daily highs reach 38 degrees or above — the proportion of heat illness patients whose symptoms developed at home rises from 6 percent to about 12 percent, roughly double the baseline rate.
Similar trends were observed in other countries that suffered severe heat this year.
In Japan, temperatures exceeded 40 degrees for five consecutive days from July 21 to July 25. During the single peak week of the heat wave, 18,591 people were transported by ambulance for heat-related illness. The most common location where patients fell ill was the home, accounting for 40.9 percent of cases.
An investigation into the deaths of 35 heat illness fatalities in Tokyo found that 74 percent — 26 people — either had no air conditioner installed or had one that was not operating.
In response, the Japanese government urged residents to use air conditioning appropriately, including at night, and designated cooling shelters across 1,255 municipalities nationwide.
France experienced its hottest June on record this summer, with the national daily average temperature reaching 30 degrees Celsius and a peak of 44.3 degrees. Red-level heat alerts — the highest tier — were issued across 72 administrative regions. From June 17 to July 2, the heat wave period, France recorded 5,764 more deaths than the same period in previous years, a 36.2 percent increase. During the peak week of June 22 to 28, home deaths rose 91 percent compared with the previous week.
French authorities found that protecting vulnerable people isolated at home was more difficult than caring for those in residential care facilities. The government subsequently focused on outreach — including cooling evacuation centers and welfare checks on elderly people living alone conducted by postal workers and neighbors.
"Compared with other countries, South Korea has a relatively low share of heat illness cases occurring at home," said Yun Ho-jung, minister of interior and safety. "But as heat waves intensify, the number of patients falling ill indoors tends to rise as well."
He added: "When the heat is severe, please make active use of cooling devices to keep indoor temperatures at a comfortable level day and night. If air conditioning is not readily available, check the location and operating hours of the nearest cooling center in advance and make use of it during heat waves."
cook@heraldcorp.com
