Your Duct System Is The Respiratory System Of Your Home Or Office. When It Becomes Contaminated With Dust, Dirt, Pollen, Animal Dander. It Becomes The Breeding Ground For Mold Spores, Bacteria, Fungus, Mildew And Other Microbes. Each Time The Furnace Or Ac Is Turned On, These Contaminants Are Circulated Throughout Your Home Or Office And Affect The Health And Comfort Of Your Staff Or Family. Most Of The Air Filters Currently In Use In Our Homes And Offices Are Of The Low Efficiency Variety Which Need To Be Changed Frequently.Most Of The Pollutants In Our Environment Are Not Stopped By These Filters And Will Contaminate And Adhere To The Inner Surfaces Of The Ducting And The Heating Ventilation Components. Only A Professional Cleaning Will Remedy This. more... See more text