Abstract: An air filter for gasoline and diesel engines that drastically improves the burning efficiency of gasoline and diesel engines is provided. The air filter includes a, replaceable filtering member made of natural fibres or synthetic fibres inside an outer box. The natural or synthetic fibres are adhered with naturally radioactive rare earth element minerals that release negative ions. The element minerals are in the form of fine powders with average diameter of 0.1 &mgr;m˜100 &mgr;m, such that when air passes through the filtering member, it is purified by the released negative ions and becomes oxygen-rich air for use in the combustion chambers of gasoline or diesel engines.

Abstract: A kind of material with ion formation capability, characterized in which on a base made of synthetic or natural material, a thin film of adhesive layer is formed. Before said adhesive film is set, fine powder of natural radioactive rare earth element minerals are spread on top of it, and through which, fine powder of natural radioactive rare earth element minerals said base may be adhered to the surface of said base through the adhesive layer and exposed in the air to let the ions formed be released in the air. Those ions can help promote body metabolism and purify air.

Abstract: An air filter for gasoline and diesel engines that drastically improves the burning efficiency of gasoline and diesel engines, featuring replaceable filtering member made of natural fibres or synthetic fibres inside the outer box of air filter; said natural or synthetic fibres are adhered with naturally radioactive rare earth element minerals that release negative ions. Such element minerals are in fine powders with average diameter of 0.1 &mgr;m˜100 &mgr;m. When the air passes through said filtering member, it will be purified by the released negative ions and becomes oxygen-rich air for use in the combustion chambers of gasoline or diesel engine.