The National Air Duct Cleaners Association (NADCA) released its 2013 Standard for Assessment, Cleaning and Restoration of HVAC systems, which includes information on assessing new and existing HVAC systems; evaluating and verifying the  cleanliness of HVAC system components; preventing jobrelated hazards; and cleaning and restoring HVAC systems to a specific level of cleanliness. The standard recommends that inspections be performed before and after HVAC cleaning and restoration projects to help the contractor determine the system’s current state, the scope of work, and the tools and equipment needed.

It also recommends a system be cleaned when it is contaminated with an accumulation of particulate, its performance is compromised due to contamination buildup, it discharges dirt or debris and projects an odor, it becomes contaminated with construction debris or dust, or it has been contaminated due to fire, smoke or water damage.