A filter media comprising: a first, wet-laid layer comprising: a first phase including a first plurality of fibers and a second plurality of fibers different from the first plurality of fibers; and a second phase including a third plurality of fibers and a fourth plurality of fibers different from the third plurality of fibers, the third plurality of fibers being the same as or different from the first or second plurality of fibers and the fourth plurality of fibers being the same as or different from the first or second plurality of fibers, wherein the air permeability of the first plurality of fibers is greater than the air permeability of the second plurality of fibers and the air permeability of the third plurality of fibers is greater than the air permeability of the fourth plurality of fibers, and wherein the air permeability is determined using a handsheet produced exclusively by such fibers and having a basis weight of 100 g/m 2 according to the standard ISO 9237; wherein the first phase, referred to as an open phase, is a phase having a larger air permeability and/or a smaller pressure drop than the second phase, referred to as a tight phase; and a second layer attached to the first layer, wherein the second layer is a nanofiber layer. a first, wet-laid layer comprising: a first phase including a first plurality of fibers and a second plurality of fibers different from the first plurality of fibers; and a second phase including a third plurality of fibers and a fourth plurality of fibers different from the third plurality of fibers, the third plurality of fibers being the same as or different from the first or second plurality of fibers and the fourth plurality of fibers being the same as or different from the first or second plurality of fibers, wherein the air permeability of the first plurality of fibers is greater than the air permeability of the second plurality of fibers and the air permeability of the third plurality of fibers is greater than the air permeability of the fourth plurality of fibers, and wherein the air permeability is determined using a handsheet produced exclusively by such fibers and having a basis weight of 100 g/m 2 according to the standard ISO 9237; wherein the first phase, referred to as an open phase, is a phase having a larger air permeability and/or a smaller pressure drop than the second phase, referred to as a tight phase; and a first phase including a first plurality of fibers and a second plurality of fibers different from the first plurality of fibers; and a second phase including a third plurality of fibers and a fourth plurality of fibers different from the third plurality of fibers, the third plurality of fibers being the same as or different from the first or second plurality of fibers and the fourth plurality of fibers being the same as or different from the first or second plurality of fibers, wherein the air permeability of the first plurality of fibers is greater than the air permeability of the second plurality of fibers and the air permeability of the third plurality of fibers is greater than the air permeability of the fourth plurality of fibers, and wherein the air permeability is determined using a handsheet produced exclusively by such fibers and having a basis weight of 100 g/m 2 according to the standard ISO 9237; wherein the first phase, referred to as an open phase, is a phase having a larger air permeability and/or a smaller pressure drop than the second phase, referred to as a tight phase; and a second layer attached to the first layer, wherein the second layer is a nanofiber layer.