Willis Carrier is considered to be the father of modern air conditioning. This article shows how air washers used in one of his first air-conditioning designs have real applications for the 21st century. Air washers can simultaneously cool, dehumidify and filter supply air, with a filter effectiveness rating of 95% in filtering out contaminants 5 microns or larger. The article’s cost comparison between an air washer and an indirect chilled water coil system shows air washers cost less to purchase and operate.