Bioaerosol and microbial exposures from residential evaporative coolers and their potential health outcomes: A review

Abstract

Evaporative cooling is one of the oldest and most energy efficient forms of air conditioning used in hot, dry climates. Historically, there are several examples of passive evaporative cooling methods, which relied on natural airflow. In the Southwest U.S., Native Americans splashed water on the tops of arbors in hot weather, which may have cooled the shaded area under the arbor by as much as 10 degrees. 1 Similar approaches were used by Western U.S. settlers who covered wall openings with damp burlap. 2,3 Other historic examples include the practice in India of hanging "tatties", wetted screens made from the roots of khus khus (cuscus) grass, over windward doorways and window openings during hot summer months, 3,4 and the introduction of water into wind towers in traditional Middle Eastern architecture. 5,6 Early mechanical methods incorporated the use of fans to improve airflow across wetted media. As early as 1905, British soldiers' barracks in India were air conditioned by arranging tatties over fans to cool supply air coming into the building. 7 In the early 1930s in the Southwest U.S., homemade evaporative coolers were fashioned by covering a wooden box with burlap or other cloth. An electric fan