Does the initial pressure wave of a nuclear explosion already carry radioactive contaminants?

Submitted by Freak_at_war t3_y20jkh in askscience

Let's focus on a ground or low air burst. Nuclear fallout describes the radioactive contamination of particles that got pulled up into the atmosphere by the hot air and fall down eventually and spread out with the wind. But say you were caught at the edge of a nuclear blast and followed basic "duck and cover" procedures. you wait for the pressure and backdraught to pass and immmediately take protecrive measures afterwards. did you get (significantly) contaminated with radionucleids even before the first fallout comes from above?

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Synaps4 t1_is0yrua wrote

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.

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kernal42 t1_is17ts9 wrote

This is correct. Waves (including pressure waves) don't transport particulates. When I sing, the air in my lungs does not get transported into the ears of those who hear me. By the same token, if my house's windows get blown out by the shockwave of a nuclear blast there won't (yet) be any radioactivity from the blast deposited in my house.

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Wonko-D-Sane t1_is29qnb wrote

Yeah, this... light travels way faster than "pressure", and the thermal and/or ionizing EM radiation from the flash is probably your death sentence in terms of radioactivity.

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