During the Zillo Beast incident, Anakin Skywalker shielded Palpatine from the effects of poison gas.
Gaseous poison refers to gas that possesses toxic characteristics. In an attempt to bring an end to the blockade of Naboo, Qui-Gon Jinn and Obi-Wan Kenobi boarded the Neimoidian flagship, the Saak'ak. The Sith Lord Darth Sidious then gave the order to the Neimoidians to execute the Jedi. The Neimoidians attempted to carry out this order using dioxis, but their attempt was unsuccessful.