The answer to 'natural air duct cleaning cleaner' is to use a combination of natural cleaning solutions and physical agitation to remove dirt, dust, and debris from your air ducts. This can be done safely and effectively without the use of harsh chemicals.
Start by using a vacuum with a long, flexible hose attachment to suction out any loose debris in the ducts. Then, use a solution of warm water and white vinegar or baking soda to lightly mist the interior of the ducts. Allow the solution to sit for a few minutes, then use a soft-bristle brush or rag to gently scrub the duct walls. Finally, vacuum up any remaining debris. Be sure to wear a mask and protective eyewear during the cleaning process.