Ask HN: How to protect your nose from nasty smell?

The perineal favorite is Vicks VapoRub daubed copiously on the top lip just under each nostril.

There isn't much that can overwhelm that solution although something like a liquefied sealed body bag that's been stewing in the sun for a few days does manage to seep through when first opened.

Not sure why you're downvoted. Vick's under the nose does drown out most smells. And the decomposing body comment is on-topic, as this is a trick that is common in law enforcement and medical roles.

The previously mentioned Vicks or cigar tricks are good and cheap.

If you don't want to mask it, then you could try a respirator with activated charcoal filters (like for painting and staining).

Rag doused in cologne held to the nose and/or a cigar (burns slow)... it's a stereotype in movies for a reason.