阅读理解

　　Parents who smoke often open a window or turn on a fan to clear the air of second-hand smoke, but experts now have found another smoking-related threat to children's hearth：third-hand smoke．

　　That's the expression which is used to describe the invisible yet poisonous gases that stick to smokers' hair and clothing and other things in the room．These gases stay long after smoke has cleared from the room．Young children can get them on their hands, especially if they are playing on the floor．

　　“Everyone knows that second-hand smoke is bad, but they don't know about this,”said Dr．Jonathan P．Winickoff, the lead author of the study at Harvard Medical School．

　　“When their kids are out of the house, they might smoke．Or they smoke in the car．They think it's okay because the second-hand smoke isn't getting to their kids．”Dr Winickoff continued．

　　Third-hand smoke is what one smells when a smoker gets in an elevator(电梯)after going outside for a cigarette, or in a hotel room where people smoked．“Your nose isn't lying．”he said．“The smell is so bad that your brain is telling you：‘Get away’”．

　　But far fewer people realized the risks of third-hand smoke．Since the expression is so new, the researchers asked people if they agreed with the statement that“breathing air in a room today where people smoked yesterday can harm the health of children．”Only 65％ of nonsmokers and 43％ of smokers agreed with that statement．

　　“The central message here is that simply closing the kitchen door to take a smoke is not protecting the kids from the effects of that smoke,”said another doctor．“There are substances(物质)in this third-hand smoke, and they are a cancer risk for anybody of any age who comes close to them．”

　　The fact that third-hand smoke is harmful will most probably lead to a strict smoking ban(禁止)at home．