eli5: How does nuclear fallout emit radiation, and does it include the air?

Question

From my understanding, nuclear fallout happens when dust or debris becomes irradiated. But does this include the air molecules even with the absence of dust?

And lastly, if you had some, say sand that was contaminated by fallout, how does the radiation emitted work? Would it be similar to heat? In the sense the closer you are to the sand you would feel more heat? I get really confused with why it’s just dust and debris, and how far they can emit radiation.

Thank you kindly in advance 🙂

In: 3

Answer 1

It’s just like an incandescent lamp!

The closer you are the brighter (more radioactive) the area because more radioactive particles are hitting you.

As for your question about the air; it can happen, it’s called ionization and is what lightning is. It’s the charged particles glowing, however in radioactive ranges they’re even more energetic and can actually hurt you! They hurt you by acting like little bullets that rip your DNA to bits and then your body has to put all the pieces back together again but it isn’t perfect.

So like a light, the closer you are to the light the more light that hits you and the brighter you are, the closer to a radioactive thing the more particles being emitted by it are hitting you.

So when we have an area that is irradiated, the dust and other material is more important because they actually get lodged inside you and continue to emit radiation. That’s why you need a filtering mask for radioactive areas – so you don’t get radioactive dust in your lungs.

If you need some visualization here imagine it like you draw a circle then draw two lines going in almost the same direction. They’ll start close but drift farther and farther. Now imagine that this is happening in a specter with radioactive particles. The farther from the source the farther apart the emitted particles are, because of the angle they left at. Now this is happening hundreds of times a second in random directions. That means if you’re farther from a radioactive item there’s a lower chance you’ll be in the line of fire than if you’re close to it.