Air showers are specialised antechambers which personnel must pass through before entering cleanrooms in order to decontaminate. Decontamination is done by clearing off dust and dirt particles from bodies of cleanroom personnel to minimize contamination of equipment or products. Designs to an air shower unit include single-side shower, double-side shower, three-side shower, and top shower. Spraying wind speed is around 25 m/s or above through stainless steel nozzles. HEPA filters are generally used to filter out particles greater than 0.3 micrometres in size from the shower air.