Illustration: Suzy Amakane

Surviving the Dreadful Heat of Summer is
More Difficult Than Surviving in the Jungle!?

A tropical rain forest is full of danger. Just stay there, and sweat will pour down your face. Japanese summer is much hotter and damper. The average global temperature is increasing year after year, and Japan marked an increase of 3.2℃ in the past 100 years. Strikingly, in Tokyo, the period of 30℃ or more is twice as long in the 2000's as that in the first half of 1980's.

The summer in Japan is hotter and
damper than a jungle or desert

The Japan Weather Association sets the "heat/humidity index", which represents heat and humidity, to analyze uncomfortable summer heat and humidity. They recognize a day with temperature of 30℃ and humidity of 75%, or heat/humidity index of 85 or over, as a "day of intense heat/humidity." They applied this "heat/humidity index" to weathers across the world and discovered that Japan went ahead of hot and humid Jakarta and Cairo as having a desert climate and took the first place in the period from the end of July to the beginning of August. Japanese summer is far more dreadful than previously imagined.

To prevent a heatstroke, the first thing to do is cool the body. It is easy to cool your hands with cold water. It is also effective to apply an ice pack wrapped in a towel to the neck or armpits. If you are desirous of a stronger sensation of coolness, drip mint oil in water, moisten a towel with it and apply to the body. You will feel cooler and refreshed. This is the effect of menthol, a major compound of mint, which is linked to the secret of a cold receptor.

"TRPM8" makes menthol feel cool and refreshed

Research revealed that our body has the TRP channel family of cell sensors that detects temperature. Among them, "TRPM8" detects cold when menthol activates it and makes the brain feel cool. Menthol-containing body paper products to wipe off sweat is supported by scientific evidence.

Menthol-containing paper, if placed in a refrigerator before use, will enhance the cooling effect because the synergy between "cold" and "menthol" activates "TRPM8." If you find mint in the jungle, you should pluck a leaf, then smell and chew it to feel cool and refreshed. When you go hunting, you should take mint water. Tear and put a peppermint leaf in water to dissolve menthol into water. Be careful: Spearmint looks similar, but does not contain menthol. Also, watch out for fierce animals hidden in dense shrubbery.

Click here to find out the secrets of TRP channels