Neither ventilation nor filtration, even in combination, can reduce tobacco smoke exposure indoors to levels that are considered acceptable.

通风或过滤，甚至两者相结合，都不能将室内接触烟草烟雾降低到被认为可接受的程度。

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Brachial artery flow-mediated dilation (FMD), a measurement of blood vessel function in the upper arm, decreased as tobacco smoke exposure levels increased among participants.

肱动脉血流调控舒张功能(FMD)是上臂血管功能的一个测量指标，会随着研究对象二手烟暴露水平的升高而降低。

youdao

There is no safe level of exposure to second-hand tobacco smoke.

关于二手烟草烟雾，不存在安全接触水平。

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

VOA: special.2009.01.13

"Exposure to tobacco smoke is a risk factor for cardiac disease already in adolescents, and that's why this study supports that children and adolescents need smoke-free environments."

VOA: standard.2010.03.04

They found that nonsmokers exposed to tobacco smoke were more likely to experience psychiatric distress, and that the mental health issues increased along with the tobacco exposure.

VOA: standard.2010.06.15

Dr Siegfried believes the hormone may exacerbate the effects of exposure to tobacco smoke - and to other substances known to be linked to lung cancer such as the gas radon.

BBC: Lung cancer risk greater for women

For these reasons, they are unable to demonstrate whether an observed reduction in hospital admissions was due to measurable reductions in exposure to tobacco smoke or to other factors, such as the long-term continuing decline in heart disease rates, other factors that may affect smoking prevalence, changes in other risk factors for heart disease, or mere chance fluctuations.

FORBES: Do Smoking Bans Really Save Lives? If So, Whose?

Most studies are based on imprecise recall and anecdotal evidence concerning the exact amount of exposure to environmental tobacco smoke.

BBC: NEWS | Health | Cancer alert for smoking parents