Quitting IS an option
Alright, all you smokers out there. Enouuuugh. It makes you smell, it makes your breath stink, it discolours your teeth, it gives you lung cancer, it's disrespectful to anyone who has lost someone to cancer, it pisses off parents with small children sitting near you, it makes you look like a relic of ancient times AND it contributes to our planet's plastic problem.
Think of all the itsy-bitsy plastic filters inside all your cancer sticks - where do they go? Then take a look at this poor jellyfish with a lovely bit of Philip Morris cigarette wrapper lodged inside it. I know jellyfish are just glutinous blobs that are hard to empathise with, but those cigarette wrappers are inside fish that you've probably eaten, too.
While telling someone their breath stinks is probably not the right way to go about convincing anyone to quit smoking, sometimes things just can't be sugar-coated. If someone you know is a smoker, perhaps try to find what it is that would motivate them enough to quit. Is it vanity? Perhaps the foul breath and teeth discolouration would be a good angle. Are they avowed environmentalists? Then maybe mentioning the plastic involved in cigarettes would help.
And, yes, you'll feel like a sanctimonious nag for berating them about their gross habit, but you may also spur them into quitting. And that could save their lives. Look at you, you life-saving superhero, you.