7 . E-cigarettes are increasingly being used as a nicotine (尼古丁) alternative (替代品) as smokers look for ways to kick their habit — and then stay off cigarettes for good. E-cigarettes work by heating a pure liquid called e-juice — made up of flavorings, propylene glycol, glycerin and often nicotine — until it changes into gas.

The use of vaping (电子烟) for tobacco stopping became especially popular in the UK after a study found that e-cigarettes helped 50,000 to 70,000 smokers in England give up smoking in 2017.

It is said that vaping cleared the 7,000 or more chemicals found in a burning cigarette and its smoke, many of which are harmful, according to Johns Hopkins medicine.

But their use has become controversial (有争议的) in the US and other countries because of warnings about possible long-term health effects, possibly from ingredients besides nicotine in the vape juice or cartridge. The US Surgeon General says vapes can contain “ultrafine substances that can be taken deep into the lungs, flavorants such as diacetyl, a chemical linked to serious lung disease, volatile organic compounds and heavy metals, such as nickel, tin, and lead.”

What's more, countless studies found teen use is a direct gateway to traditional cigarette smoking at a time when teenager use of e-cigarettes was increasing.

A 2019 outbreak of a mysterious vaping-related lung disease among American youth has triggered alarm as well. As of February 2020, the condition had killed at least 68 people and sickened more than 2,807, according to the US Centers for Disease Control and Prevention.

One 18-year-old American who vaped for over a year ended up in the hospital with “lungs like a 70-year-old.”

The condition, now known as EVALI (e-cigarette or vaping use-associated lung injury), is strongly linked to e-cigarettes containing vitamin E acetate, a sticky oil substance that can cling to lung tissue.

8 . How to boost your immune system

On the whole, your immune system does a remarkable job of defending you against disease-causing microorganisms.    1    Is it possible to fight the disease off? What if you improve your diet? Take certain vitamins or herbal preparations? Or make other lifestyle changes?

Now, researchers are exploring several factors, hoping to help you strengthen your immune system.

    2    Following general good-health guidelines is the single best step you can take toward naturally keeping your immune system working properly. Every part of your body, including your immune system, functions better when protected from environmental assaults and boosted by healthy-living strategies.

Like any fighting force, the immune system army marches on its stomach.    3    Scientists have long recognized that people who live in poverty and are malnourished are more vulnerable to infectious diseases.

Modern medicine has come to appreciate the closely linked relationship of mind and body. A wide variety of sicknesses, including stomach upset, and even heart disease, are linked to the effects of emotional stress.    4    

Regular exercise is one of the pillars of healthy living.    5    But does it help to boost your immune system naturally and keep it healthy? Just like a healthy diet, exercise can contribute to general good health and therefore to a healthy immune system.

9 . According to a survey, more young people are killed each year by sleepy drivers than by drunk drivers. This proves one thing. Getting enough sleep can be tough. How are we dealing with the problem? Sleep clinics (诊所) are appearing all over the United States.     1    

Driving when tired can be very dangerous. During the daytime, over half of drivers report feeling sleepy at some point. At night, over 80 percent drivers sometimes get drowsy (昏睡的). And here is the most frightening of all.     2    

What is going on here? One thing is that people are not getting enough sleep. One person out of three gets by on less than six hours a night. Lots of people have trouble falling asleep.     3     Few people get enough of the deep sleep they need to feel really rested.

    4     Believe it or not, people need seven to nine hours of nighttime sleep to remain healthy. During that sleep, a person’s immune system is built up. This helps fight off diseases and infections. And taking a nap in the daytime does not really help. It will make a person feel refreshed. But it cannot make up for the lack of nighttime sleep.

What if you are a person with real sleeping problems? What if you have tried all the home remedies (治疗法) like hot milk? You might consider going to a sleep clinic.     5     They will study your sleep problems, and you will not have to pay anything.