A recirculation filter includes a first layer and a second layer. The
first layer has a first side and a second side and is configured to trap
particles that are of a first size. The second layer has a first portion
adjacent to the first side of the first layer and a second portion
adjacent the second side of the first layer. The second layer is
configured to trap particles that are of a second size. The second size
of particles trapped by the second layer is greater than the first size
of particles trapped by the first layer.