To remove oil afloat in the air to clean environments and prevent the blade of a ventilating fan and a duct from being contaminated by the oil by first soaking pulp fibers or chemical fibers in water together with a peat moss and stirring them, then charging the mixture into a mold to be dried into a peat paper and applying an adhesive padding which is used for clothes to the peat paper.

A peat moss is in the form of a fine powder with pores into which oil is absorbed. Unless oil is absorbed beyond the level of the required absorption by the peat moss, the absorbed oil does not stick to any object around again. The peat moss, pulp and fiber such as polyester are soaked in water and are stirred, and further are charged into a paper making implement or the like to be dried, so that the peat moss is coagulated. In addition, an adhesive padding 2 to be used as a lining for clothes is applied to the peat paper 1 made as described to increase the strength of the paper 1, which is, in turn, used as a constituent for the oil filter 3. When this oil filter 3 is used, it is mounted on a ventilating fan or the like, and the oil content of air passing through the ventilating fan or the like is efficiently absorbed by the oil filter 3.