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.