Chemical sterilization uses chemical sterilants to treat surgical instruments and medical supplies. Each sterilant performs distinctively and has a specific purpose. Ethylene oxide, or ETO, is a colorless gas that kills spores and microorganisms by interfering with their metabolic processes. ETO sterilizers are used to decontaminate heat and moisture-sensitive devices, such as resuscitation bags. The items are first cleaned and rinsed with demineralized water to remove contaminants, detergents, or tap-water residues. Then they are put in packs, filled into baskets or carts, and placed inside the sterilizer chamber for a specified time. During sterilization, numerous items absorb ETO. These items must be aerated to allow evaporation and removal of residual ETO. Liquid chemical sterilization is used for heat-sensitive, immersible, medical devices. The devices are submerged in an active sterilant solution for a prescribed time at a controlled temperature and concentration to kill all possible microorganisms and their spores. Then these devices are rinsed with water to clear the chemical remains. Examples of sterilant solutions include formaldehyde, glutaraldehyde, and hydrogen peroxide.