They measured levels of a byproduct of cigarette fumes in the kids' saliva to gauge smoke exposure and had parents fill out a questionnaire about the kids' emotional, behavioral and social problems.

他们检测儿童唾液中一种香烟副产物的水平以估测香烟烟雾接触度，并让家长填写一份关于儿童情感、行为和社交问题的调查表。