Electronic cigarettes are to be banned on Southern trains from late July 2015.
The train company is the latest in a long list of organisations to ban "vaping".
It joins sports stadiums, high street shops and some hospitals.
The bans are controversial. In most cases, they aren't on health or legal grounds, but for the comfort of other people, and to avoid confusion over "real" and "fake" cigarettes.
Campaigners say e-cigarettes are a safer alternative to traditional tobacco and that banning them will remove an incentive for people trying to give up.
Over 2.6 million people smoke them every day according to the smoking charity Ash. So where can you still vape if you want to?
From 26 July, Southern will ban vaping on its trains and platforms - Thameslink and Great Northern have already banned them, as have Transport for London.
Virgin, Northern and Cross Country have banned them, as have some others.
If you're a vaper and live in Kent though, you're in luck. Southeastern still allows vaping on its trains and platforms.
This one, again, depends a bit on where you are flying from and who with.
Generally speaking, vaping is banned on most flights and some particularly smoky devices will still set off alarms in the toilets. The primary exception is Ryanair, which doesn't allow e-cigarettes on board but does sell its own "smokeless" cigarettes, which aren't electronic and work like nicotine inhalers.
In fact, forget smoking, just trying to work out where you can carry your e-cigarette on planes is tricky. Some countries' laws say they should be carried in checked baggage, whilst some say they need to be carried in the cabin as the batteries are a fire risk.
But how about at the airport? Almost every airport in the UK has expressly banned vaping indoors. The only exception is London Heathrow, which allows passengers to vape until they are at their flight gate. Others can allow it, but most have chosen not to.
On coaches and buses
Best to check with the operator. National Express? It's a no. If you get caught, the company say you'll be booted off the bus with no refund.
They are also banned on all London buses. But some local companies may be quite happy for you to.
Manchester City, Manchester United and Chelsea are among the big name clubs who've said no to vaping. Both have banned electronic cigarettes in their stadiums. In fact, one Man City fan was handcuffed and had his season ticket suspended specifically because he used an e-cig in the Etihad stadium.
That case was quickly reversed, but the ban on e-cigarettess still stands.
Burnley, on the other hand, has designated "vape friendly" zones and sponsorship deals with vaping companies. So it really depends who you support.
Hospitals in Scotland have banned e-cigarettes, even on hospital grounds, not just inside buildings. Only the NHS Lothian trust will allow vaping, in designated smoking areas. In England and Wales, there's no blanket ban, but some hospitals have gone out on their own and stopped people from smoking e-cigarettes.
Again, there is no blanket rule. Most pubs will probably let you smoke an e-cigarette, although it's worth checking first. There are some big-name chains, however, which have banned them, including Starbucks, Caffe Nero, All Bar One, and KFC.
Wales has put forward plans to give e-cigarettes the same status as traditional tobacco, which would mean a broad ban in enclosed spaces. Vapers are safe for now, though, as the law is just in the planning stages.