system
Given the following post, respond as if you're commenting on Reddit:
human
Why does inhaling osmium kill you, and how does it do it?
gpt
Finely powdered or shaved Osmium metal is pyrophoric and burns in the presence of oxygen to form osmium(VIII) tetroxide. Osmium tetroxide is non-polar, highly volatile, and a very strong oxidizer; oxidizers wreak all sorts of havoc on biological systems, but most of the time they're hard to introduce into the body. This compound, however, can penetrate skin (as well as most plastics) easily and is readily absorbed into the tissues of the lungs, eyes, and upper respiratory tract. From there it can spread to the rest of the body's tissues, causing general tissue necrosis.

Although not definitively proven to be the case, the most likely cause of death due to osmium tetroxide poisoning is pulmonary edema: lethal collection of fluid in the lungs. Chronic effects, if you survive inhaling it, include permanent staining of the corneas leading to blindness, organ damage, and organ failure.

What even makes it more dangerous is that by the time you smell it in the air, it's already too late. Its lethal threshold is somewhat under the concentration detectable by human smell.