It is a rather good plot playing on the ideas going around society today - if we cut down all the trees what will we do for oxygen? Crossan manages to weave a delicate complex story with well-developed characters that is enjoyable and engrossing. My favourite character is Alina but the two friends who rescue her from the law enforcers of the Pod smuggling her outside are also extremely like-able. All Crossan's characters are such that you want to find out what happened to them.
Breathe is one of those novels where the story is split between several viewpoints - in this case between Bea, Alina and Quinn (unfortunately not as fit as Quinn from the Night World series!)
Alina is the rebel, the one who knows what the Premium government are up to, whose dedicated her life to fighting it - despite the horrific consequences if she's found out (one of which is to be left slowly suffocating from lack of air on the Outside). She is very strong, and from the start of the novel is detached and unwilling to form any attachments to anyone, romantic or just friendly.
Bea is an Auxiliary who is best friends with a Premium. When she fails to gain admittance onto a program she should have got onto, and her friend does, she begins to doubt the fairness and validity of the whole set-up. Bea is very caring and isn't afraid to form attachments unlike Alina. Once she befriends Alina she begins to represent Alina's humane side making Alina more humane and less detached than she previously was.
Quinn is a Premium, son of one of the high-up politicians. He's friends with Bea and when she doesn't get on the above mentioned program he too begins to doubt the system. Bea and Quinn help Alina out of the Pod when she reveals she's in trouble to them - despite having never really met them before. Quinn is strong and brave but having been brought up by some-one who is in the corrupt system is unable to really believe that it is really corrupt until later on in the book.
I enjoyed Breathe and will look for the next book in the series and grew attached to the 3 main characters and their journey to reach the rebels. I think Crossan has managed to set herself up well for the next novel and I really want to read it now to find out how Alina gets on and whether the other two manage to catch up!