A purification device for disinfecting and filtering intake air is disclosed. The purification device comprises a housing provided with a number of inlet perforations for allowing the intake air to enter the housing and a number of air outlet perforations for allowing air purified by the purification device to leave the housing. The purification device moreover comprises a fan arranged inside the housing to suck the intake air into the housing and blow the purified air out of the housing. The purification device further comprises an ultraviolet radiation lamp arranged inside the housing to irradiate the intake air. The purification device also comprises a high-efficiency particulate air (HEPA) filter arranged to filter the intake air before the intake air leaves the housing as purified air. The filter comprises a plurality of pleats arranged in such a manner that the angle between adjacent pleats is 30 degrees or less.