Dorset Group offers biological air washers for laying hens and pigs. The hen washer has the capacity to clean 70 percent annual amount of barn odor with a capacity of 2 cubic meters/hour, according to the company. The pig washer has a 90 cm high filter layer and 50 meters squared for cleaning a maximum of 100 cubic meters per hour, Dorset says. The systems can be equipped with or without a central ventilation system and are custom-made on request.