The National Air Duct Cleaner's Association (NADCA) has granted final approval to the most comprehensive set of air duct cleaning standards crafted in the United States. The standards are expected to be released in mid-August.

The standard has been developed over the past two years by a NADCA committee. It will recommend that hvac systems be cleaned based on a regularly scheduled basis and provide details about how clean the systems should be.

Additionally, the proposed standard states that such cleanliness inspections should be conducted "without negatively impacting the indoor environment through disruption of settled dust, microbial amplification or other debris." In cases where that isn't feasible, or contamination might result, "environmental engineering control measures should be implemented," the proposed standard says.