Yogyakarta. High temperatures inside homes can significantly increase the risk of heat-related illness among older adults, according to new research by Gadjah Mada University (UGM), highlighting a growing public health concern as extreme heat becomes more frequent.

The study, conducted in Yogyakarta, found that the average indoor temperature in homes occupied by elderly residents reached 31 degrees Celsius (87.8 Fahrenheit).

Researchers also found that every 1-degree Celsius increase in the temperature difference between indoors and outdoors was associated with a 32% higher risk of heat stress, suggesting that dangerous heat exposure is not limited to outdoor environments.

"People often assume the main danger comes from being outside, but indoor temperatures can also pose serious health risks, particularly for older adults," Aditya Lia Ramadona, a lecturer at UGM's Faculty of Medicine, Public Health and Nursing, said on Friday.

The Meteorology, Climatology and Geophysics Agency (BMKG) said the country's average air temperature between June and July 2026 reached 27.3 degrees Celsius (81.1 Fahrenheit), about 0.7 degrees Celsius above the long-term climatological average for the period.

Ramadona said one of the most severe consequences of prolonged heat exposure is heat stroke, a life-threatening medical emergency that occurs when the body can no longer regulate its temperature.

"In simple terms, the body loses its ability to control its temperature. Body temperature rises rapidly, cooling mechanisms such as sweating are no longer effective, and vital organs and the brain begin to malfunction," he said.

Symptoms of heat stroke include extremely high body temperature, confusion, slurred speech, seizures, and loss of consciousness.

Despite Indonesia's tropical climate, Ramadona said many people still underestimate the dangers of extreme heat because hot weather is often viewed as a normal part of daily life.

The research also found that a 1-degree Celsius increase in average weekly temperature was linked to a 15.5% rise in visits by mothers and children to primary healthcare facilities in Yogyakarta, suggesting that heat exposure may have broader health impacts beyond older adults.

To reduce the risk of heat stress and heat stroke, researchers recommend drinking plenty of water, wearing lightweight and breathable clothing, avoiding strenuous outdoor activities during the hottest part of the day, seeking shade or cooler indoor spaces, and recognizing the early symptoms of heat-related illness. Exercise and physically demanding work should be scheduled for the morning or late afternoon when temperatures are lower.

Ramadona said adapting to rising temperatures will require more than individual behavioral changes. He called for Indonesia to develop heat early warning systems, adjust school and working hours during extreme heat, strengthen protections for outdoor workers, and improve the capacity of the healthcare system to respond to heat-related illnesses.

"Extreme heat is no longer just uncomfortable weather. It has become a public health issue and a challenge to social resilience," he said.

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