Negative Air Pressure Machine

Air duct cleaning is an important aspect of household cleaning and a good way to remove indoor air pollution from the breathing air. The source removal method creates negative air pressure within an air duct system to contain debris within the workspace. The negative air pressure creates an inward airflow that keeps debris from flowing out of the system and into the air under the principle that air flows from high pressure to lower pressure.

Via greentairductcleaning.com

Air duct cleaning is important for eliminating indoor air pollution and ensuring healthy breathing air in your home. Source removal is the most effective method of air duct cleaning in which the vents are sealed off and negative air pressure is created to remove all dust and debris build-up. Use of the negative air pressure machine for source removal is the only NADCA approved method of air duct cleaning.