Studies have confirmed that the higher the ventilation rate, the faster the number of droplet particles in indoor air decays. Lack of ventilation or low ventilation rates increase the rate of airborne infections and disease outbreaks. Fresh air system is a set of independent air treatment system composed of air supply system and exhaust system, both ducted fresh air system and ductless fresh air system through the fresh air machine to purify the outdoor air into the indoor, through the duct will be discharged indoor air, increase ventilation can reduce the chances of disease infection, the office environment to prevent infection or with a mask and diligent hand washing.