[Graphic News] Heat-related illnesses hit third-highest level since 2011

South Korea reported 4,066 heat-related illness patients in 2026, according to the Korea Disease Control and Prevention Agency. The figure was the country’s third-highest since nationwide monitoring began in 2011. It shows that heat remained a major health threat even though the total was lower than the previous year.

The 2026 patient count fell from 4,460 in 2025, a decrease of 394 cases. However, estimated deaths increased. Emergency-room reports linked 36 deaths to heat-related illnesses between May and September, up 24 percent from a year earlier.

Older people were especially affected. Those aged 80 and older accounted for 17 deaths, or 47.2 percent of the total, compared with 10 deaths last year. Deaths among people under 80 stayed unchanged at 19. The contrast between fewer cases and more deaths highlights the severity of some heat episodes.

A heat-related illness is a medical problem caused by the body absorbing or producing more heat than it can safely manage. The term covers a range of conditions, from milder problems such as dehydration, heat cramps, and heat exhaustion to heatstroke, a medical emergency involving dangerously high body temperature and impaired brain function.

For example, prolonged heat exposure can cause heavy sweating, weakness, dizziness, nausea, or confusion. If the body can no longer cool itself, heatstroke may develop. That can damage vital organs and become fatal without urgent treatment. These details are established medical knowledge; the source article does not list specific illness types.

The 2026 South Korean monitoring total combines heat-related illness patients reported through the national system. It counted 4,066 patients and estimated 36 deaths between May and September. The high numbers show why medical surveillance matters, even when the country experiences fewer officially counted heat-wave days.

The number of heat-wave days does not capture every part of heat exposure. A season can have fewer officially counted heat-wave days yet still include short, severe episodes. In 2026, South Korea recorded 22 heat-wave days, compared with 29.7 in 2025 and 30.1 in 2024, but illnesses remained numerous.

The clearest example came from August 1–10. That period accounted for 38 percent of all reported patients and 44.4 percent of estimated deaths. Its average daily high temperature was 34.4 degrees Celsius, which was 2.9 degrees higher than during the same period a year earlier. Such concentrated intensity can drive rapid health impacts.

The result was 4,066 patients, the third-highest total since monitoring began nationwide in 2011. The agency’s figures show that total heat-wave-day counts alone may not describe the health burden. The severity and timing of hot periods also matter.

The August 1–10 period was the clear peak of South Korea’s 2026 heat-health crisis. Its average daily high temperature reached 34.4 degrees Celsius. This was 2.9 degrees higher than the average daily high during the same period in 2025, showing an unusually intense burst of heat.

The concentration of illness was striking. August 1–10 accounted for 38 percent of all reported heat-related illness patients. It also accounted for 44.4 percent of the estimated deaths reported through emergency rooms. The figures indicate that a short period can carry a large share of a season’s health burden.

This peak helps explain why illnesses stayed high despite fewer heat-wave days overall. South Korea recorded 22 heat-wave days in 2026, down from 29.7 in 2025 and 30.1 in 2024. The August figures show why heat intensity matters alongside duration.

Extreme heat can cause dehydration, heat exhaustion, heatstroke, and other medical emergencies. Heatstroke is the most dangerous form because the body’s cooling system fails and core temperature rises rapidly. Without prompt treatment, it can damage organs and cause death. These medical details are established knowledge; the article reports the resulting cases and deaths.

Older adults can be especially vulnerable because aging may reduce the body’s ability to regulate temperature and maintain fluid balance. They may also have chronic health conditions or take medicines that affect heat tolerance. The source does not list these mechanisms, but they are well-established medical explanations for increased risk.

South Korea’s 2026 figures show the danger clearly. People aged 80 and older accounted for 17 of 36 estimated deaths, or 47.2 percent. That was up from 10 deaths the previous year. Deaths among people under 80 remained unchanged at 19.

South Korea’s 2026 total was historically high. The Korea Disease Control and Prevention Agency reported 4,066 heat-related illness patients, ranking the figure third-highest since nationwide monitoring began in 2011. This places 2026 near the top of the country’s recorded heat-health burden.

The ranking is notable because the annual total declined from 4,460 patients in 2025. South Korea also recorded fewer heat-wave days in 2026: 22, compared with 29.7 in 2025 and 30.1 in 2024. Even so, the number of patients remained high enough to enter the top three.

The record provides context for the season’s danger. It shows that a lower annual heat-wave-day count does not necessarily produce a low illness total. The article does not identify the two years with higher totals, but it makes clear that 2026 remained an unusually severe year in the monitoring record.

The human body normally keeps its internal temperature within a narrow range. When it gets too hot, the brain’s temperature-control system triggers sweating and sends more blood toward the skin, helping heat escape. People also reduce activity or seek cooler surroundings, which lowers heat production. These are established physiological facts, not details stated in the article.

Under intense or prolonged heat, sweating can cause substantial fluid loss, while hot air can limit the body’s ability to release heat. If cooling cannot keep pace, internal temperature rises. Heat exhaustion may progress to heatstroke, when temperature control breaks down and vital organs can be damaged. Heatstroke requires emergency medical care.

The South Korean data show the consequences of this risk. The country recorded 4,066 patients and 36 estimated deaths in 2026. Cases peaked during August 1–10, when average daily highs reached 34.4 degrees Celsius and 44.4 percent of estimated deaths occurred.