The jury is still out on whether regular duct cleaning is beneficial. Also, no study has shown that cleaning ducts is effective in preventing health problems. The presence of dust or soil within heating and cooling air ducts hasn’t been linked conclusively with increased dust levels inside the home.

 

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Outdoor pollutants entering the home, plus indoor activities such as cooking, cleaning, or smoking, have been shown to cause more indoor air pollution than that introduced by ductwork.

Regular duct cleaning by a qualified professional contractor won’t do any harm. On the other hand, improper cleaning can aggravate indoor air-quality problems. HVAC professionals who service furnaces and air-conditioning equipment generally don’t perform duct cleanings, but they may be able to provide references to reputable firms that do so. When considering cleaning contractors, check with state regulators and/or the local Better Business Bureau, and be certain to ask for and check references from prior customers before making any decisions.

The U.S. Environmental Protection Agency says ducts should be cleaned if any of the following conditions are visible inside the ducts:

 

• Substantial mold
• Evidence of rodent or insect infestation
• Excessive dust and debris
  

The presence of any of these problems is frequently a symptom of other problems inside the home. For example, moisture from condensation, plumbing leaks or other sources can cause mold growth anywhere, including the insides of ductwork. Duct cleaning will remove the mold, but the underlying problem also must be corrected.

To prevent contamination inside a forced-air heating/cooling system:

 

• Use the highest efficiency air filter recommended by the manufacturer of your heating and cooling system.
• Change filters regularly, before they become clogged. 
• Be sure air cannot bypass filters through gaps around the filter holder.
• When having a cooling system maintained or checked for other reasons, be sure to ask the service provider to clean cooling coils and drain pans.
• During construction or renovation work that produces dust, seal off supply and return registers and do not operate the heating and cooling system until after cleaning up the dust.
• Reduce dust by vacuuming regularly. Use a high efficiency vacuum (HEPA) cleaner or the highest efficiency filter bags your vacuum cleaner can take. Vacuuming with poor filtration can increase the amount of dust in the air during and after vacuuming – dust that may end up in your ducts.
• If your heating system includes in-duct humidification equipment, be sure to operate and maintain the humidifier as recommended by the manufacturer.