Should people suffering from asthma clean air ducts more often?

It depends on what substances trigger their Asthma attacks. Allergens commonly found in homes and in the air ducts are pollen, dander, and mold spores. Note that I didn't say that mold grows in air ducts. It happens, but not nearly as often as you might have been led to believe.

Mold spores, however, are nearly impossible to prevent in the home environment, and it is inhaling these mold spores that can trigger asthma attacks in individuals sensitive to asthma.

Air duct cleaning can be an important part of the asthma management plan. The main focus of any plan should be on reducing exposure to allergenic triggers.

Especially if they have tried everything else and they are still having asthma attacks, air duct cleaning could make all the difference. This is even more important to consider if they did air duct cleaning in the home a couple of years ago already, and they have noticed a steady decline in the success of their allergy management.

Then it might just be time to clean the air ducts again, especially the blower motor and the evaporation coils on the heating and cooling equipment, which can become encrusted with allergenic particles that get past the filters.

If the asthma sufferer does not have Allergies, and reacts instead to changes in temperature or the like, then it is unlikely that air duct cleaning would help too much.