Cigarettes aren't just harmful when they're being smoked. Even when cigarette ends go out and are cold, new research has found they continue to give off harmful chemicals in the air. In the first 24 hours alone, scientists say a used cigarette end will produce 14 percent of the nicotine（尼古丁） that an actively burning cigarette would produce.
While most of these chemicals are released within a day of being put out, an analysis for the United States Food and Drug Administration （FDA） found the level of nicotine fell by just 50% five days later.
"I was absolutely surprised," says environmental engineer Dustin Poppendieck from the United States National Institute of Standards and Technology （NIST）. "The numbers are significant and could have important impacts when cigarette ends are dealt with indoors or in cars. While much attention has been paid to the health influence of first-hand, second-hand and now third-hand smoking, it is not the case when it comes to the actual cigarette end of the matter."
To measure emissions（排放） from this forgotten thing, Poppendieck and his team placed 2，100 cigarettes that were recently put out inside a special room. Once the ends were sealed away, the team measured eight chemicals commonly produced by cigarettes, four of which the FDA have their eye on for being harmful or potentially so.
After setting the room's temperature, the researchers tested how emissions changed under certain conditions. When the air temperature of the room was higher, for instance, they noticed the ends produced these chemicals at higher rates. This finding might discourage those who want to leave ashtrays（烟灰缸） out for days at a time, especially in the heat.



What do the researchers say about cigarette ends？ ______

A. They contain little nicotine.
B. They produce no nicotine 5 days later.
C. They give off nicotine for days.
D. They create as much nicotine as burning cigarettes.

What do Poppendieck's words suggest？ ______

A. First-hand smoking does most harm.
B. The findings are within his expectation.
C. Cigarettes should be dealt with indoors.
D. Health influence of cigarette ends is ignored.

Which word best describes the authors attitude to not cleaning ashtrays for days？ ______

A. Unclear.
B. Disapproving.
C. Unconcerned.
D. Puzzled.

What can be the best title for the text？ ______

A. Used Cigarette Ends Release Harmful Chemicals
B. Cigarettes Are More Harmful While Being Smoked
C. Research Found Reasons for Cigarette Ends' Harm
D. Cigarette Ends Produce More Chemicals in the Heat