Surely 9 months is barely enough to catch up on the existing literature on the topic.

No the main radiation exposures are the initial flash and the fallout but the pressure wave is ...well pressure...so you are still only being touched by the same air particles that were in your local area before and they are being pushed by the ones next to them etc. Theres not much transport of particles over long distances in a pressure wave; you need wind to do that, or you need to make things radioactive by direct radiation... Which is possible but not a significant factor if you're far away... which you are because the initial fireball hasn't incinerated you.