Air showers are specialized enclosed antechambers which are incorporated as entryways of cleanrooms and other controlled environments to reduce particle contamination. Air showers utilize high-pressure, HEPA- or ULPA-filtered air to remove dust, fibrous lint and other contaminants from personnel or object surfaces. The forceful "cleansing" of surfaces prior to entering clean environments reduces the number of airborne particulates introduced.

When properly incorporated into cleanroom design, air showers provide an ISO-classified transition vestibule to ensure the cleanliness of the classified cleanroom. Air showers are typically placed between a gowning area and cleanroom; after workers don appropriate garb and personal protective equipment, they enter the shower so that the pressurized air nozzles remove any residual particles from coveralls. Once the program cycle is complete, users exit out through a second door, into the cleanroom. Air showers (or air tunnels) may also be placed between cleanrooms of different ISO ratings.

Interlocking mechanisms are a common air shower feature to prevent both exits from being opened simultaneously, which would allow outside air to enter a tightly controlled environment. This requires occupants to stay inside until the decontamination cycle has completed. For this reason, safety features such as emergency stops are required by most safety administrations. Alternatively, the air shower may consist of a long tunnel not equipped with doors; personnel slowly walk through to reach the controlled area. Air handling equipment creates an isolated atmosphere using pressure differentials to create fluid boundaries between the inner and outer environments.

From Wikipedia