Number of heatstroke patients in Japan jumps fourfold amid sweltering temperatures

The number of patients rushed to hospitals for heatstroke over the week through Sunday quadrupled from the week before as the mercury hit 40 degrees Celsius in some cities amid a sweltering heat wave, preliminary data from the Fire and Disaster Management Agency showed Tuesday.

Over that period, 9,105 people sought emergency hospital care for suspected heatstroke across the nation, more than twice the number during the same period last year.

Those age 65 and above accounted for 5,378, making up 59.1% of the total.

By prefecture, Tokyo had the most heatstroke-related transports at 907. Aichi came in second with 763 cases.

By location from where patients were transported, those who were found at their home made up the largest proportion at 37.9%, followed by on public roads or sidewalks, at 20.6%.

Patient numbers are likely to increase in the weeks to come, which is expected to put a strain on hospitals.

As a preemptive measure, the Nagoya Institute of Technology’s Advanced Medical Physics and IT Research Center recently launched a website that provides heatstroke patient-intake estimates for hospitals in eight prefectures including Tokyo, Osaka, Aichi, Hokkaido and Hiroshima. Two more prefectures will be added next month.

Akimasa Hirata, a professor of mechanical and biomedical engineering and director of the research center, said the estimates will help hospitals make preparations, such as by anticipating how many ambulances will be required.

The institute’s estimates are based on the wet-bulb globe temperature index — which takes into account air temperature, solar radiation and humidity — and data for 140,000 former heatstroke patients.

In Tokyo, a total of 7,112 people were taken to hospital due to suspected heatstroke between June and September last year — the highest in five years. Of those suspected cases, 3,502 occurred in July.

According to statistics from the Tokyo Fire Department, the number of ambulance calls spikes when the temperature hits between 25 C and 35 C and humidity is in the range of 50% to 80%.