What is worse, inhaling second hand smoke or smoking cigarettes?

Second-hand: Assuming your frequency of exposure to cigarettes is the same as primary vs secondary exposure, the second-hand smoke is worse because it's not filtered and it contains more ash and combustion by-products.

"Second Hand" Myth: I am not an advocate of smoking and there are lot's of reason to quit smoking but "Second Hand Smoke" is not one of them. The expression "second-hand smoke" is a very effective piece of anti-smoking propaganda used all the time by public health officials and physicians yet there is absolutely no scientific evidence to support it's existence. It's logical to conclude but not proven in any study.

Risks less but there: While the odds are less, secondhand smoke has been linked to the development of emphysema and heart disease, just like smoking. So not as intensely risky as smoking, but still risky. People who live with smokers do need to be careful and mind their own health.

Both are bad: and can cause cancer COPD and other problems. Primary smoking is probably worse.