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We all know health is the most important in our life and we know smoking is harmful to people's health. But not many people know about the danger of second-hand smoke.
Second-hand smoke is the smoke that comes from the smoker's breath.If people breathe in second-hand smoke from time to time,they could get sick from it.It can cause lung cancer（肺癌）and many other diseases.
But how serious is the problem of the second-hand smoke? The World Health Organization (WHO) did a study of 194 countries.They found that second-hand smoke causes about 600,000 deaths every year.That is about 1% of the world death and it leads to a lot of trouble and pain.
Second-hand smoke is especially harmful to children because their bodies are growing. According to a study, around 165,000 children under 5 die each year because of second-hand smoke. Most of these deaths happened in Africa and Southern Asia where health care is very poor.
You can do something to keep yourself and other people away from second-hand smoke. You can ask the smokers, such as your parents, to smoke outside. And, if someone smokes close to you, you'd better hold your breath or just walk away.
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