Not really a problem with new tech...
The bulging issue is a known issue with that generation Lithium batteries. It doesn't happen often, and the conditions are pretty well know that cause it to happen...
The current generation, those in the current version of the Air are not going to suffer from that kind of problem. Battery issues are going to be so few, there are tons of other things that can happen from your laptop first. This said, if you attempt your own battery repair, and you somehow cause lithium to be exposed to the air, well good luck to you...