“Parts Per Billion” is the type of film that stretches for profundity, but can only reach a punishing ambiance of despondency. Taking on the end of the world, writer/director Brian Horiuchi struggles to create a dynamic doomsday vibe while tending to the intimate details of humanity as it struggles with the inevitable. More dull than devastating, “Parts Per Billion” can’t kickstart a convincing mood of panic, instead resting on tedious existential discussions and relationship woes while stringing together a useless cat’s cradle of character connections, forgoing the larger portrait of desperation to keep everything linked in a contrived manner. Read the rest at Blu-ray.com