How do the construction sites keep the dirt from getting in people's lungs?

They don’t. They just get better lawers. Who claim that the dust came fron somewhere else.

You must mean that you don’t know of any who do.

@flo Edit. You are right I don’t know.

They keep it watered down.

They wear masks or kerchiefs or get dust in their lungs that they probably shouldn’t.

They don’t. The lungs are really effective at clearing minor annoyances out quickly.
Bigger annoyances, like Miner’s Black Lung Disease, is a different story.
If you’re approaching a dusty construction site and you know your lungs can’t handle it, take a different route.

Measures are taken, but dust does happen.
Construction sites are very common. People need to be their own keeper. If you are prone to breathing issues, you should carry a fiber mask (like painters use) scarf, or other means of filtering particulants from the air you breathe. Preparedness is key.

I don’t think dust from plain organic dirt is usually more than a nuisance to healthy humans, is it?

I don’t see anything to be terribly worried about on this site about dust .

But of course there are things like masks and so on.

Are you saying that there are no construction sites that keep the dirt in? That’s the OP about.
@kritiper I meantined the watering in my detail.

Thanks for the link @Zaku

What if there is an easy (not expensive etc.) fix by the construction site?

The only “fix” would be masks. But I doubt the workers would wear them. They aren’t sissies.

@flo Yes you did, and I missed it because it was in the details, not the main question. My bad.
I see a few construction workers wearing particle masks, but many don’t wear them. I see masons cutting stone and tile and they wear no protection. I’ve seen men who drive crawler tractors in the Inland Empire of Eastern Washington state, who are black with dust at the end of the day but wear no protection.
It’s not enough of a problem to be concerned about. There is always going to be dust of some kind, no matter what. And the lungs can work that out.

Have you read the whole article in @Zaku,s post?

@kritiper No problem.