A nasal filter includes a main body, a cover, and a filtering medium. The main body has a hollow cylinder, a boss connected to a spherical member, a flange, and a plurality of internal guide vanes. The hollow cylinder has a front and a rear opening. A first threaded portion is formed on the outer surface at the front end portion of the hollow cylinder. A thru hole is formed on the cover and aligns correspondingly to the front opening of the hollow cylinder. A second threaded portion is formed on the inner surface of the cover for mating to the first threaded portion on the hollow cylinder. The filtering medium is held in between the cover and the hollow cylinder and covers the thru hole. A filter pad is further included to provide additional functions. Accordingly, the nasal filter offers air purification and doe not cover the mouth.
