You're likely thinking of ethylene oxide, which is a gas commonly used to sterilize medical equipment and other materials. It's a powerful antimicrobial agent that effectively kills bacteria, viruses, fungi, and spores.

However, it's important to note that ethylene oxide is a hazardous substance and should only be handled by trained professionals in controlled environments.

Other gases used for disinfection include:

* Chlorine gas: Used in water treatment and some industrial applications, but it's highly toxic.

* Ozone gas: A powerful oxidizer with disinfecting properties, often used for air and water purification.

* Hydrogen peroxide vapor: An effective disinfectant, especially for sensitive medical devices.

It's crucial to be aware of the risks associated with any disinfectant gas and follow proper safety protocols.