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.

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Minutes after she left her bedroom on the lower level and went upstairs, the smoke alarm went off and she saw "thick black smoke" coming from downstairs.

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The image is grainy, but good enough to be able to fly at very low level at night, although rain, fog, or smoke adversely affect it.

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Smoke travels upwards, and if smokers are confined to the top level and adequate ventilation is in place (be it an open window or a small fan), then there can be no cause for concern to those non-smokers who sit downstairs.

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