A new study says more American and Canadian teenagers are vaping than ever before. Vapes are electronic devices that heat liquid into a cloud of vapor that users inhale. Most users vape with a liquid that includes the drug nicotine, several other chemicals and flavoring.

The researchers examined data on smoking and vaping by young people in Canada, England and the U.S. They found that between 2017 and 2018, the number of 16- to 19-year-olds who reported vaping in the past 30 days rose by almost 50% in the U.S. The number almost doubled in Canada.

Britain saw little change in vaping numbers.

Researchers say the availability of vapes with more nicotine may be responsible for increased usage.

David Hammond, with the University of Waterloo in Canada, led the study. He said in an email that "2018 marked the point at which new vaping technology started to take over the market, led by JUUL."

JUUL vapes went on the market in 2015. The researchers noted that the company now commands more than half the vape market. JUUL became available in Britain in July 2018 and in Canada in September 2018.

Teen use of JUUL vapes increased in all three countries during the study period. The percentage of U.S. teens who reported using JUUL products regularly between 2017 and 2018 increased from 1% to 4.5%.

Hammond said many young people think vaping is not harmful and do not know the nicotine levels of vaping products. He added, "Parents and kids should know that these products are capable of producing addiction and may have long term health risks..."

In an emailed statement, JUUL said, "We don't want any non-nicotine users to use our products, especially youth." The company said it had taken aggressive action in the U.S. and Canada to fight underage use of its products.

Linda Bauld is the head of public health at the College of Medicine and Veterinary Medicine at the University of Edinburgh in Scotland. She says parents should talk to their children about the dangers of smoking and vaping.

She told Reuters in an email that "parents should explain that vaping products are for adult smokers trying to quit, not teenagers who have never smoked."

Bauld added, "Vaping is less harmful than smoking, that's why it is a good option for adult smokers. But that doesn't mean that it is risk free and it is better for teenagers to use nothing - no vaping, no smoking."

I'm Jonathan Evans.

Adapted from: http://www.hxen.com/englishlistening/voaenglish/voaspecialenglish/2019-07-14/521126_2.html

1. vaping n. 蒸发，是吸入和呼出气溶胶的行为，通常称为蒸汽，它是由电子香烟或类似装置产生的。

2. inhale v. to take air, smoke, gas, etc. into your lungs as you breathe 吸入；吸气。例如：

 She closed her eyes and inhaled deeply. 她合上双眼，深深吸了一口气。

 He inhaled deeply on another cigarette. 他又点了一根烟深深地吸了一口。

3. addiction n. (不可数名词, 可数名词) addiction (to sth.) the condition of being addicted to sth. 瘾；入迷；嗜好。例如：

 cocaine addiction可卡因瘾

 He is now fighting his addiction to alcohol. 他现在正努力戒酒。

 1. More American and Britain teenagers are vaping than ever before. 

 2. Vapes are electronic devices that heat liquid into a cloud of vapor that users inhale. 

 3. Most users vape with a liquid that includes the drug nicotine, several other chemicals and flavoring.

 4. The researchers examined data on smoking and vaping by young people in Canada, England and the U.S. 

 5. They found that between 2017 and 2018, the number of 16- to 19-year-olds who reported vaping in the past 30 days rose by almost 50% in the U.S. The number almost doubled in Britain.

 6. Canada saw little change in vaping numbers.

 7. Researchers say the availability of vapes with more nicotine may be responsible for increased usage.

 8. David Hammond, with the University of Waterloo in Canada, led the study. 

 9. JUUL vapes went on the market in 2015. The researchers noted that the company now commands more than half the vape market. JUUL became available in Britain in July 2018 and in Canada in December 2018.

 10. Teen use of JUUL vapes increased in all three countries during the study period. 

 11. Hammond said many young people think vaping is not harmful and do not know the nicotine levels of vaping products. 

 12. Linda Bauld says parents should talk to their children about the dangers of smoking and vaping.

 13. Bauld added, "Vaping is less harmful than smoking, that's why it is a good option for young smokers. But that doesn't mean that it is risk free and it is better for teenagers to use nothing - no vaping, no smoking."

û 1. More American and Britain teenagers are vaping than ever before. (正确表达) More American and Canadian teenagers are vaping than ever before. 

ü 2. Vapes are electronic devices that heat liquid into a cloud of vapor that users inhale. 

ü 3. Most users vape with a liquid that includes the drug nicotine, several other chemicals and flavoring.

ü 4. The researchers examined data on smoking and vaping by young people in Canada, England and the U.S. 

û 5. They found that between 2017 and 2018, the number of 16- to 19-year-olds who reported vaping in the past 30 days rose by almost 50% in the U.S. The number almost doubled in Britain. (正确表达) They found that between 2017 and 2018, the number of 16- to 19-year-olds who reported vaping in the past 30 days rose by almost 50% in the U.S. The number almost doubled in Canada.

û 6. Canada saw little change in vaping numbers. (正确表达) Britain saw little change in vaping numbers.

ü 7. Researchers say the availability of vapes with more nicotine may be responsible for increased usage.

ü 8. David Hammond, with the University of Waterloo in Canada, led the study. 

û 9. JUUL vapes went on the market in 2015. The researchers noted that the company now commands more than half the vape market. JUUL became available in Britain in July 2018 and in Canada in December 2018. (正确表达) JUUL vapes went on the market in 2015. The researchers noted that the company now commands more than half the vape market. JUUL became available in Britain in July 2018 and in Canada in September 2018.

ü 10. Teen use of JUUL vapes increased in all three countries during the study period. 

ü 11. Hammond said many young people think vaping is not harmful and do not know the nicotine levels of vaping products. 

ü 12. Linda Bauld says parents should talk to their children about the dangers of smoking and vaping.

û 13. Bauld added, "Vaping is less harmful than smoking, that's why it is a good option for young smokers. But that doesn't mean that it is risk free and it is better for teenagers to use nothing - no vaping, no smoking." (正确表达) Bauld added, "Vaping is less harmful than smoking, that's why it is a good option for adult smokers. But that doesn't mean that it is risk free and it is better for teenagers to use nothing - no vaping, no smoking."