Mercury vapor is a form of the element mercury that exists as a gas at room temperature. It is produced when liquid mercury evaporates, and it can be found in various applications, such as in fluorescent lamps and some types of thermometers. Exposure to mercury vapor can be harmful to health, as it can be inhaled and absorbed into the body. It is important to handle mercury and its compounds with care to prevent potential toxicity and environmental contamination. Proper safety measures should be taken when working with or disposing of mercury-containing products.