Filtrete Allergen Reduction Filter, 18 in. x 30 in. x 1 in., 4/Pack. As you manage your allergies on a day to day basis, you're looking for options that can help reduce allergens in your air. Filtrete Allergen Reduction filters turn your central heating and cooling system into a whole house air cleaner. With electrostatic technology, these filters help reduce airborne allergens from air passing through the filter.