Can I aply for a passport in Brazil while on holiday?

I'm temporarily in Brazil but normally live in another country; can I apply for an Irish passport here?

No, you must apply in the country you are normally resident in.

You should only apply to the Consulate General in São Paulo only if you reside in Our Consular Area or in the case of a lost/stolen passport while visiting here.

If travelling on a passport, it must be valid.