Introduction

Introduction In recent years, ventilation duct cleaning has grown into a huge industry, in response to surging public concern about indoor air pollution. The industry claims that cleaning ductwork can improve indoor air quality, control molds and other allergens, enhance heating, ventilating, and air‐ conditioning (HVAC) system performance, and reduce energy costs. Yet there is little scientific evidence to support these claims, and poor duct cleaning practices can actually cause or increase air quality complaints. This fact sheet provides guidance on when duct cleaning may be appropriate, how to protect building occupants during duct cleaning, and how to prevent the conditions that drive facility managers to undertake this costly procedure.