1. Each year, people die from second hand smoke.

2. Each year, people die from second hand smoking.
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Which one is okay? Are both expressions acceptable? Which one is commonly used, 'secondhand smoke' or 'secondhand smoking'?

"second hand smoke" is better. "Smoking" implies you're doing it yourself, not inhaling someone else's smoke, so doesn't work as well. The meaning is clear, but...