This is 99% invisible. I'm Roman Mars.

Ronnie Johnson still remembers the first time he went underground.

He and a handful of other coal miners piled into a little trailer and descended into the mine.

We were going down through their hitting bumps and running over little rocks and stuff.

And I remember laying in that little trailer and the roof was actually so close to me

that the bill by my heart had with almost 50 root.

When they got down to the bottom Ronnie's boss handed him a wrench and told him to open a nearby water line.

But someone had forgotten to cut the water off.

Like water just started spraying me.

You just sprayed all in my base and all over me out of something wet.

And it's like I just like fell up against the real, you know, the wall or coal.

And I thought to myself, what have I done?

As a new miner in a dangerous industry, Ronnie had to go through an intensive orientation process

before this first trip underground.

That's producer Irene Zhorov.

Ronnie is actually my partner's father.

He lives in Northern Alabama and on a recent visit as the family cooked dinner.

Ronnie and I went out to his workshop where he likes to sit and smoke with only the dogs

and cicadas for company.

Or somewhere else you want to do it here or somewhere I don't care.

We can just go back there.

He told me about how he sat through 40 hours of training and safety classes

...