Are Japanese growing less heat-resistant?
“Elderly person dies at home of heat prostration.” “High school swimmer succumbs in mid-practice; ambulance called.”
These sort of headlines have become all too familiar lately. In July alone, 31 people died of heatstroke; 18,407 were taken by ambulance to hospital.
It’s hot, of course – still, isn’t there something odd here? Global warming and the heat island effect are facts, but Japanese summers have always ranged from hot to searing, to say nothing of humid, and yet people coped – without air conditioners if you go back 40 years, without electric fans if you go back 60. A sprinkling of cold water on the skin, a bamboo curtain to screen the sun – and life went on.
Why, in this age of artificial comforts en masse, are people suddenly so vulnerable to so universal a phenomenon as summer heat?
“Are Japanese bodies growing less heat-resistant?” asks Shukan Post (Aug 15-22).
Summers undeniably are hotter lately than they used to be, but not enough so to account for the epidemic of heatstroke or heat exhaustion. A more relevant fact seems to be the aging society – more than half of the relevant ambulance calls are from people aged 65 or over. Heat, the magazine hears from Shinshu University Prof Hiroshi Nosei, causes blood vessels to expand, which accelerates blood flow, which activates the sweat glands to produce cooling sweat.
As we age, however, this process wears down. Sweat comes less readily to the elderly. There are more elderly than ever before – therefore, more heatstroke.
Yes, but what of the frequent reports of teenage athletes collapsing on the field? That, too, seems unprecedented.
Here the evidence is contradictory. When experts disagree, the general public find it hard to draw conclusions. On this much at least there is basic agreement: sweat pores form in the first three years of life in response to the environment – more in hot climates, fewer in cold. An average Japanese born in a hot zone would develop some 2.8 million pores; in a temperate zone, 2.3 million; in a cold region, 1.9 million. The more pores, the more sweat.
What was the effect on pore formation of the advent of mass air conditioning in the 1980s? This is where disagreement arises, with some experts saying the influence of air conditioning has been decisive, others saying no. Even granting that young people sweat less profusely today than two or three generations ago – which has not, they insist, been proven – other factors must be considered, not least a degree of enlightenment among high school sports coaches, who used to forbid drinking water during practice, perhaps to heighten endurance, but no longer do.
The worst heatwave in recent memory hit in 2010 – 1,745 people are known to have died from its effects – and yet, says one of Shukan Post’s expert sources, “almost none were children.
So if we’re reading more than ever before lately about heatstroke, the point, says Nosei, “is not that the Japanese have grown less heat resistant but that the number of vulnerable Japanese” – specifically the elderly – “has grown.”
Which, adds Shukan Post, gives the media a chance to fill a slow news season with dire warnings about something which, even when not deadly, is miserably familiar to all of us – heat.