Ellens post is excellent because it addresses Formic Acid
specifically.
However, in other posts there are general references to acids
which lump their properties together. Mine was one. I listed the
strengths, actually the ph relationships, of Formic, Oxalic and
Sulfuric. Problem is, that is not enough, and I apologize for the
post. Each Acid has its own characteristics. Formic appears
nonpoisonous while Oxalic is. We eat acetic and tout honey and
vinegar as a folk remedy.
You can get serious burns with a weak acid, depending on the
chemical activity of the acid. That goes for the vapors. Some
acids can be stored in plastic. Some will eat right through it.
When I was in graduate school we would be reminded of the dangers
of different chemicals by the deaths of chemists working on them.
And these were experienced professionals working with all
precautions. I knew of two working in my discipline.
We have not even addressed the long term effects of breathing
small amounts of the vapors or minor skin contact. Both can lead
to serious problems later.

Bill T
Bath, Me