Do the following to ensure the safe operation of your smoke detector: if your smoke detector is working properly, the red light should be on.

为确保您的烟雾探测器的安全运行，请执行以下操作：如果烟雾探测器正常工作，则红灯常亮。

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"When you look at the biology, there is no safe level of exposure to tobacco smoke," he says.

他还说：“当你看了生物学以后就会发现，任何级别的烟雾含量都是不安全的。”

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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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But clearly there is no such thing as a safe level of cigarette smoke exposure.

VOA: special.2009.06.03

"Our goal is to make a very inexpensive stove let's say five dollars that makes very,very little smoke, so it's safe for health, diminishes global warming and diminishes deforestation.

VOA: special.2010.02.01

Nearby,Marina Pirozhnivona, recounted how her 86-year-old aunt died last Saturday after experiencing breathing problems on a day when wood smoke pushed city carbon monoxide to almost seven times safe levels.

VOA: standard.2010.08.10

Her stance was backed by the British Heart Foundation and Cancer Research UK, who said there was no safe level of smoke and that the ban on smoking indoors should be absolute.

BBC: Wales smoking ban forced Casualty story change says

The mayor assured city residents that the air is safe, despite lingering concerns over asbestos, chemical fumes and smoke.

CNN: New York issuing 'recovery notes' to help city rebuild

But the robber made off with cash from the safe and the Rosebery Avenue post office was badly damaged by smoke.

BBC: Hampden Park post office in Rosebery Avenue, Eastbourne