大熱天跳到冷水中或致命,即使你會游泳大綱

It's a scenario many of us daydream about during a heat wave while stuck in a badly ventilated office or on a stuffy commute. Being able to cool down by plunging into a cold lake or have a dip in the sea sounds pretty blissful when temperatures peak at 31.9C.

大熱天被困在通風不好的辦公室或悶熱的交通工具中時，我們都會幻想這樣的場景：當氣溫高達31.9度時，能夠跳到冰涼的河水中或在海中暢遊降暑。

But while this may sound fun and refreshing, it can actually be incredibly dangerous - deadly even. This is because at the root of large number of drownings is cold water shock. A condition which is rarely discussed, cold water shock can trigger a deadly heart attack. You may not think anything of having a refreshing swim in the cold water, but with the average temperature of the sea off UK shores between 10 to 15C, the RNLI warn this is in fact cold enough to cause cold water shock.

雖然這聽起來令人身心舒暢，但實際上卻非常危險--甚至會致命。這是因爲大量溺水事件的根本原因在於冷水衝擊。很少有人談論這一情況，但冷水衝擊可能會引發致命的心臟病發作。也許，你並沒有打算在冰冷的河中游泳，但英國海岸海水的平均溫度爲10至15度，英國皇家全國救生艇協會警告稱，這種溫度足以導致冷水衝擊。

Professor Mike Tipton, author of the book Essentials of Sea Survival, has said: "If you are lucky enough to survive long enough to die of hypothermia, you have done very well. Most die in the first minute of immersion." "It's cold water shock that tends to kill people around our shores," the RNLI warns on their website.

《海上生存要領》（Essentials of Sea Survival）一書的作者邁克·提普頓教授說道："如果你足夠幸運，能長時間在低體溫的境況下存活，那你就已經很棒了。大多數人在浸下去的第一分鐘就沒命了。""在岸邊游泳時，導致人們死亡的原因往往是冷水衝擊，"英國皇家全國救生艇協會在網站上警告稱。

What happens to your body when you jump into cold water? Cold water will put your body through a number of physiological responses. The first is one the considerable lowering of your skin's temperature, which being one of the "most profound stimuli the body can encounter" is a potentially a big strain on your body's resources.

跳入冷水中你的身體會發生何種變化？冷水會讓你的身體歷經多種生理反應。首先就是皮膚溫度大幅度降低，這是"身體能遇到的最大刺激"。於身體而言，這可能是一個巨大的壓力。

The RNLI continues: "The responses tend to be short lived, but threaten survival." You'll find your blood vessels start narrow, reducing the amount of blood which can circulate. "The heart then has to work harder and blood pressure increases," the RNLI explains.

英國皇家全國救生艇協會繼續道："身體的反應往往是短時間的，但卻會威脅你的生命。"你的血管會開始變窄、減少血液循環。"之後，心臟運作更爲困難，血壓升高，"英國皇家全國救生艇協會解釋道。

"At the same time there is a 'gasp' response, which can result in water being breathed in rather than air. The breathing rate changes dramatically, it can increase by as much as tenfold. "

"同時，還會出現'喘息'反應，導致人們吸入水而非空氣。呼吸速率急劇變化，甚至能加快10倍。"