How can you politely ask someone to stop smoking?
How to Be a More Polite Smoker
Smokers, be aware of your surroundings. The world doesn't revolve around you. Non-Smokers, the world doesn't revolve around you either.
I encourage smokers to consider that the smoke doesn't just disappear when it leaves your area. Smoking on your balcony or in your backyard is a perfectly acceptable practice unless you realize your neighbor is having a party in their backyard or is enjoying a pleasant day with their windows open. When you see that your smoke will drift into the area of the party or you hear your neighbor shutting their windows, your grown-up responsibility is to extinguish your cigarette or move to another location. If you want to raise the manners bar, head over to your neighbor's home, politely apologize, and let them know they are clear to open their windows again. Your neighbor will be amazed and your stock will rise.
Manage Your Cigarette Butts Responsibly
My final request to smokers is that you manage your cigarette butts responsibly. I hope you wouldn't tell your kid to throw his or her candy wrapper on the street, and so you shouldn't flick your cigarette butt out the window of your car--or drop it anywhere on the ground, frankly. Cars are equipped with an ashtray. And trash cans and butt receptacles are everywhere, at least here in the United States. Just fully extinguish the fire before putting the butt into a waste bin. It's not going to be too much of a burden on you to hang on to your butt for a bit until you find an appropriate receptacle.
How Should Non-Smokers Treat Smokers?
Now, non-smokers, listen carefully. Smokers are much like you in that they are not interested in being yelled at. It is none of your business why they smoke. In fact, asking such a rude question would be similar to asking someone why they are so overweight or why they have such horrible children. Those kinds of questions are not polite.