Aftermath: Population Zero

Being aired on NATGEO, "Aftermath Population Zero" it must be factual, right???. Wrong!!! I first noticed that there was no mention of water expanding when frozen, causing concrete cracks to expand. Then they said that the cracks exposed the re-bar in the concrete to carbon dioxide, causing the re-bar to rust. ??? Excuse me, but air consists of only 0.038% carbon dioxide, but oxygen is about 20.95%. Rust is ferrous oxide. The oxygen in the air is going to contribute 500 times more to the rusting process than carbon dioxide. Then I remembered having heard "carbon dioxide" several times before the concrete part, and noticed "carbon dioxide" continuing to be mentioned again and again. It was then that I suspected that this was more an example of poor science and propaganda than factual. I lost interest, but do not recall any mention of plant-life absorbing carbon dioxide and giving off oxygen.