Learn Spanish (Latin America): En la cueva, el polvo espeso le daña a uno los pulmones. - In the cave, the thick dust damages one's lungs.

In this sentence, uno acts as the indirect object (the person affected by the dust). In Spanish, when an indirect object is explicitly named with a (like a uno), you generally must include the matching indirect object pronoun before the verb, which is le in this case.

The translation says "one's lungs". Why doesn't the Spanish say los pulmones de uno?

While los pulmones de uno is grammatically possible, Spanish strongly prefers using an indirect object structure for actions involving body parts. By saying le daña a uno, Spanish frames "one" as the person directly experiencing the damage, rather than just pointing out who owns the lungs.

Why does the sentence use los pulmones (the lungs) instead of a possessive word like sus pulmones?

This is a classic Spanish rule: use the definite article (el, la, los, las) for body parts when the "owner" is already clear from the context. Because the sentence already established that the action happens to "one" (le ... a uno), using a possessive word would be unnatural and repetitive.

Is espeso the usual word for thick dust?