Cotinine levels in blood are often used to measure exposure to tobacco smoke.

VOA: special.2009.01.13

One is there's no lag period, notice that antibody levels start rising right away after the second exposure.

第一是没有迟滞期,请注意,抗体浓度迅速上升,在第二次接触抗原时

耶鲁公开课 - 生物医学工程探索课程节选

"We found that people with high exposure to second hand smoke had increased levels of depression and anxiety."

VOA: standard.2010.06.15

So in other words, if you live with a smoker, you really are at very high risk of demonstrating high levels of second-hand smoke exposure."

VOA: standard.2010.06.15