wrote:
Smoking is bad for you.

Yes it is.

... I wonder how fast a lit cigarette will damage
or even sever a plastic lifeline?

Depends on what the "plastic" is.
Many kinds of hi-strength line don't melt unless you get the temp much
much higher. It's rather frustrating because they need an old-
fashioned whipped end instead of just neatly melting it.

OTOH a cigarette can burn a hole in a sail in an instant.

Fresh Breezes- Doug King