All UL 181 Air Ducts and Connectors have been tested by Underwriters Laboratories, Inc. for mold growth and humidity, and are considered by the manufacturer as acceptable for use in conjunction with evaporative coolers. Please refer to Chapter 6 and Appendix B Testing, Listing, Reporting and Certifying of the ADC Flexible Duct Performance & Installation Standards (Greenbook). www.flexibleduct.org for further information.