Children aged 3-11 years have cotinine levels (a biological marker for secondhand smoke exposure) more than twice as high as nonsmoking adults.

• 3到11岁的被动吸烟的孩子与那些家长不吸烟的孩子相比，他们体内可替宁(作为二手烟吸入量的一种血液标记)的含量要高出两倍多。