With over 7,000 chemicals released each time you light a cigarette, it's no surprise that smoking is one of the leading causes of preventable deaths worldwide.
你点燃一根香烟，就会释放出超过7000种化学物质，所以吸烟是全球可预防性死亡的主要原因之一也就不奇怪了。
But with 1.3 billion people actively smoking, what actually happens when you stop smoking?
但地球上有13亿人烟民，那么停止吸烟后身体究竟会发生什么变化呢？
Within the first 20 minutes of quitting, your blood pressure and heart rate return to normal.
在停止吸烟的最初20分钟内，你的血压和心率会下降到正常水平。
This is because the nicotine in cigarettes released epinephrine and norepinephrine, which increase your heart rate and narrowed blood vessels.
这是因为烟草中的尼古丁会释放肾上腺素和去甲肾上腺素。
These facts also cause smokers extremities to feel colder, but by now your hands and feet have returned to their normal temperature.
这也会导致吸烟者感到四肢发冷，但你的手脚现在已恢复至正常体温了。
2 hours in, and the nicotine cravings begin causing moodiness, drowsiness, tense feelings, and even difficulty sleeping, because nicotine also releases more dopamine than normal.
2小时后，对尼古丁的欲望会开始让人感到情绪低落、昏昏欲睡、焦虑，甚至难以入眠，因为尼古丁也会释放过量的多巴胺。
These are expected physiological responses to the decrease in its release.
这是身体对于戒烟后8小时内对多巴胺下降的预期生理反应。
8 hours after quitting, an inhaled carbon monoxide clears, allowing oxygen levels in the blood stream to return to normal.
停止吸烟后8小时，体内吸入的一氧化碳被清除，这使得血流中的氧含量恢复正常。
Carbon monoxide and oxygen compete to bite hemoglobin in your blood, which stresses the circulatory system.
一氧化碳和氧气争先恐后地与血液中的血红蛋白结合，这给血液循环系统带来了压力。
So as it clears, there's more room for oxygen.
因此，一氧化碳清除后，氧气的含量开始增加。
However, for the long-term smokers, this carbon monoxide exposure causes red blood cells to increase in size,
然而，对于长期吸烟的人来说，长期接触一氧化碳 会使红细胞体积增大，
making the blood thicker, and causing higher blood pressure, and increases chances of developing blood clots.
导致血液变粘稠，血压升高，并且增加患血栓的风险。
Surprisingly, 24 hours after quitting, coughing will actually increase, which is your body's way of clearing out all the toxins from the lungs.
出人意料的是，戒烟24小时后，咳嗽竟然会增多，这是因为机体会把原本沉积在体内的烟尘排出体外。
Additionally, at this point, the risk of developing various coronary artery diseases decreases, all within 24 hours.
除此之外，戒烟24小时内，患各种心血管疾病的风险会降低。
After 48 hours, when nicotine and its metabolites are completely eliminated from your body, damaged nerve endings begin to regrow.
48小时后，尼古丁和其他代谢物从身体中完全排除，受损的神经末梢会开始重新生长。
The tar and other chemicals in cigarettes leave fewer taste buds that are flatter with less blood vessels.
随着血管中香烟中的焦油和其他化学物质物质含量的减少，其味蕾上的含量也在减少。
They now begin to regain their sensitivity making food taste better.
味蕾开始恢复对味觉的敏感度，所以食物尝起来更美味了。
Although chronic smokers may often have irreversibly damage to taste buds.
但长期吸烟者会经常也对味蕾造成不可逆的损害。
At the 72-hour mark, nicotine withdrawal peaks with headache, nausea, and cramps, as well as emotional symptoms like anxiety and depression.
停止戒烟72小时，尼古丁戒断高峰症状包括头痛、恶心和痉挛，以及情绪上的症状，比如焦虑和抑郁。
These symptoms can be seen by most addictive substances including caffeine.
大多数成瘾物质使用过后会出现这些症状，包括咖啡因。
But after this period, the worst is officially over.
但这段时间过后，最糟糕的情况就正式结束了。
After one month, the risk of developing Type II diabetes, cancer and cardiovasculardiseases has already decreased.
一个月后，患Ⅱ型糖尿病，癌症和心血管疾病的风险已经降低了。
In 3-9 months, the damaged cilia in the lungs are almost fully repaired, which are hair-like structures that helps sweep away dust and debris.
3至9个月后 肺部受损的纤毛几乎完全被修复了，纤毛是帮助清除肺部灰尘和碎片的类毛发结构。
And as a result, symptoms such as coughing and shortness of breath are almost completely eliminated.
因而，像咳嗽和呼吸短促等症状几乎完全消失了。
And around one year, the risk of developing heart disease, as a direct result of atheroma formation,
大概一年过后，患上动脉粥样硬化直接导致的心脏病的风险几乎降低了一半，
which are deposited fat material or scar tissues from deteriorating arterial walls, decreases by almost one half.
而动脉粥样硬化是动脉管壁不断恶化后沉积的脂肪物质和疤痕组织。
In 10 years, the chance of developing lung cancer decreases to half of someone who did not quit smoking.
10年后，患肺癌的风险下降到不戒烟的人们的一半。
And in 15 years' time, the risk of heart attack decreases to the same as someone who has never smoked their entire life.
15年后，心脏病发作的风险下降到与那些终生未吸烟的人同样的水平。
Of course, this guideline is not definitive, and the average amount you smoke per day or year will play a role in how well your body recovers.
当然了，这份指南并不是绝对的，你每天或每年的平均吸烟量会影响你的身体恢复情况。
Unfortunately, there will always be some irreversible damage to the lungs, and increaseing susceptibility to developing various lung diseases.
不幸的是，吸烟总是会对肺部造成一些不可逆的损伤，并且增大对各种肺部疾病的易感性。
And, while quitting may be difficult, the benefits greatly outweigh the initial withdrawal.
另外，尽管戒烟很难但它的好处远远大于你最初放弃的那点东西。
Ultimately, the best way to prevent this from happening is to not begin smoking at all.
最后，防止这种情况发生最好的办法就是不要开始吸烟。
Need some extramotivation? Check out our video "Dear lazy people", which might give you the boost you need to kick your habit or focus on other goals you're hoping to accomplish.
需要更多动力吗？看看我们的视频"亲爱的懒人们"吧，也许能让你有动力戒掉你的坏习惯，或者专注于希望达成的其它目标，有疑问的话请在社交媒体的评论区向我们提问。
Ask us your burning questions in the comments or on social media and subscribe for our weekly science videos every Thursday.
记得订阅我们每周四发布的每周科学视频。
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