Yes, smoking is dangerous - hence all the health warnings and price hikes - but it is also a habit which can be hard to break via the 'cold turkey' method (as much because of the psychological aspects of addiction as by the chemical addiction - which is why nicotine patches also require willpower). Added onto which, there are the conspiracy theorists who refuse to believe the health warnings: "My nan smoked 40 a day and lived to 86!"
So airports providing somewhere where smokers can engage in their habit seems a sensible idea. I'd assume it's air conditioned so keeping the concentration of smoke in the air to levels far below that of pubs in previous generations, and it wouldn't surprise me if the air pressure inside is slightly lower than outside, to minimise smoke escaping (except on the breath and clothes of the smokers).
As for alcohol / obesity, they're tougher nuts to crack. You have to consume a significant quantity of alcohol to get addicted in the first place, but the main worry nowadays isn't so much alcoholism but binge drinking - those who don't drink much during the week, but come weekends consume far too much. You'd think the side-effects (loss of memory, loss of control, vomiting, hangovers) would be a pretty sharp deterrent, but evidently not. The drinks industry is also a very powerful lobby, hence minimum pricing is fiercely resisted (usually with the excuse it would hit poor, moderate drinkers unfairly) the manufacturers that do put the number of alcohol units on their bottles / cans tend to write them in fairly small script, hidden away on the back label somewhere. Public health campaigns can play a part (e.g. "Have none for the road"), as well as advertising restrictions.
If alcohol is a tough nut to crack, obesity's even tougher. Food manufacturers are an even more powerful lobby - remember the daft story over in the US the other month that classified 2 tablespoons of tomato puree (i.e. the amount used in a pizza) as a portion of fruit/veg so it could still be sold in school lunch menus. Fast food is unhealthy by definition, but again a lot depends on consumption. If you take your children to a fast food restaurant once or twice a month as a treat, it probably won't do them much harm. If you're relying on fast food for the majority of their meals, and ordering fries and a sugary soft drink rather than a fruit bag and milk / water (bear in mind fruit juice is just as sugary as full sugar soft drinks), their weight is bound to increase. Banning fast food advertising probably would be unfeasable, but for those companies that provide healthier alternatives to the standard burger + fries + sugary soft drink, perhaps they could be encouraged to only show the healthier alternatives in their advertising (if the children in the ad are shown enjoying a fruit bag, and your children watch the ad, they may possibly consider it as an alternative to fries).