I've been having a devil of a time with little flying green guys that spit poison, and would like some form of protection. All I've seen so far is the Hazmat suit, which only gives +15%, about 1/6 blocked/received. I'm using the Frackin' Universe mod.
For vanilla, there is the poison antidote (https://starbounder.org/Poison_Antidote) which gift protection from poison for five minutes. It is rather cheap to craft (if you have a poison fluffaloo), but each dose requires a whole slot in your inventory. Or you can use the augmentation slot of your environmental protection pack to install a poison resist augment (https://starbounder.org/Poison_Resist_Augment).