Jasmine Terry in a contamination suit.
A contamination suit is a variety of specialized clothing which can be used to protect the wearer from contaminants, such as toxins or microbes, as the name suggests. Alternately, in "clean room" situations, the suit can also prevent any contamination of the outside environs from aspects of the wearer's physiology - such as their own body's flora and fauna, DNA traces, hair, or dust from skin cells and other exfoliation.
History and specifics[]
Contamination suits can use a variety of technologies to prevent contaminants from crossing into or out of the suit. A simple contamination suit could be an unsealed oversuit with electrostatic or force field technology to prevent microorganisms from crossing into or out of the suit, while still allowing the wearer to breathe the atmosphere of the surrounding environs. A more complicated model would use a complete physical seal and have a closed air source for the wearer's breathing needs, filtering out all outside gases, particle traces and microorganisms. (TOS episode & Star Trek 1 novelization: The Naked Time; TNG novel: Contamination; EV comic: "Flesh of My Flesh")