香港濕熱世界第一?濕熱比乾熱易令人中暑

經常聽到人形容香港濕熱是世界第一,那為什麼濕熱會讓人感覺比較熱?它跟乾熱的分別又在哪?原來濕熱環境會減慢身體降溫,增加人中暑的機會!

濕熱環境令身體難以降溫

熱分為兩種——乾熱和濕熱,乾熱是指濕度水平低於40%的炎熱環境,而濕熱即是指濕度水平高於40%,並有可能達到100%的時候。

濕熱的體感溫度比乾熱更高,這是因為在乾熱的環境,身體可以更有效的排汗,以達致自我降溫。汗水會不停地從皮膚上蒸發,帶走多餘的熱量,而我們唾液和呼吸中的水份亦會快速蒸發,讓人感覺口乾。相反,在濕熱的環境,高溫和高濕度令汗水難以蒸發,因此身體會更難降溫。

天氣濕熱更易中暑 酷熱天氣有潛在危險

濕熱往往比乾熱的環境危險,身體降溫慢會更容易導致過熱和中暑,而且高濕度也會讓人精力不足,有昏昏欲睡的感覺。有心理學家更指出,濕度高會影響情緒,令人心情低落。另外,雖然乾熱能加速降溫,但這反而會衍生另一種危險,因為人們會難以察覺自己過熱,導致身體脫水反而更嚴重。

中暑初期症狀不明顯

中暑的初期症狀不明顯,你可能只是感覺有點頭暈和全身無力,但之後便會出現大量出汗、噁心、頭痛、皮膚發涼、脈搏加快等病徵,所以在炎熱天氣下我們應額外留意身體狀況。如果出現過熱的症狀,我們應該立刻採取以下措施:

  • 到有冷氣或陰涼的地方休息

  • 補充足夠的水份

  • 嘗試降溫(敷冷毛巾、泡冷水)

  • 脱去不必要的衣服

參考資料:

SaltStick (2022, July 20). It’s hot: Humid vs. Dry heat. https://aletenutrition.com/blogs/saltstick-blog/its-hot-humid-vs-dry-heat

Baquero, L. (2022, July 22). Dry vs. Humid heat: NY doctor says which is more dangerous, and other hot weather perils. NBC News. https://www.nbcnewyork.com/news/local/dry-vs-humid-heat-ny-doctor-says-which-is-more-dangerous-and-other-hot-weather-perils/3785464/

Mayo Clinic (2023, April 06). Heat exhaustion. https://www.mayoclinic.org/zh-hans/diseases-conditions/heat-exhaustion/diagnosis-treatment/drc-20373253

Doudna, M. (2021, August 26). Verify: Does dry or humid heat really matter when it comes to heat exhaustion? 12News. https://www.12news.com/article/news/verify/verify-does-dry-or-humid-heat-really-matter-when-it-comes-to-heat-exhaustion/75-3d63f623-bd7a-4c4c-90ac-714c9e9d9011#:~:text=In%20dry%20heat%2C%20the%20sweat,to%20sneak%20up%20on%20people.

Sarmiento, S. (2016, August 13). It’s not just the heat, it really is the humidity: Know the risks. NBC News. https://www.nbcnews.com/health/health-news/it-s-not-just-heat-it-really-humidity-know-risks-n629486

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