Neutralizer gas was a thick, white gas that was mostly safe for humans. It was used to quell chemical fires and liquefy toxic gases. The Galactic Empire's Distillery on the planet Coyerti had neutralizer gas–equipped vents that were used when a rebel squad detonated a chemical barrel inside the compound in 3 ABY. The squad's four soldiers found it hard to see through the gas when they then went inside the mostly-evacuated Distillery to plant explosives.
Brand (pictured) was familiar with neutralizer gas.
During the time of the Galactic Empire, an Imperial Distillery that produced bioweapons on the Mid Rim planet Coyerti had a ventilation system equipped with neutralizer gas. In 3 ABY, the Rebel Alliance's 61st Mobile Infantry launched a campaign on Coyerti and sent a squad of four led by First Sergeant Hazram Namir to destroy the Distillery. As part of the attack, the rebel soldier Brand infiltrated the compound and planted a microdetonator on a toxin barrel in order to create a distraction.
When the detonator exploded, neutralizer gas was released to nullify any poisons that had been released while workers there evacuated. Having seen the gas before, Brand advised her squadmates about the neutralizer gas, and the four soldiers moved into the Distillery to plant timed explosives, wearing gas masks. The gas adversely affected the squad's visibility, and any flames sparked when they fired at remaining Imperials were shortly put out. The Distillery was ultimately destroyed by the explosives.
Neutralizer gas appeared in the 2015 novel Battlefront: Twilight Company, written by Alexander Freed.