Air duct cleaning service providers may tell you that they need to apply a chemical biocide to the inside of your ducts to kill bacteria (germs) and fungi (mold), and prevent future biological growth. Some duct cleaning service providers may propose to introduce ozone to kill biological contaminants. Ozone is a highly reactive gas that is regulated in the outside air as a lung irritant. However, there remains considerable controversy over the necessity and wisdom of introducing chemical biocides or ozone into the duct work.
On the other hand, if family members are experiencing unusual or unexplained symptoms or illnesses that you think might be related to your home environment, you should discuss the situation with your doctor. EPA has published the following publications for guidance on identifying possible indoor air quality problems and ways to prevent or fix them.
I believe a $3 [sic] pleated cotton filter is all that is ever needed to keep a system running top notch. A cleaning of the blower squirrel cage and of the evaporator [indoor] coil may be needed one time if fiberglass or no filters have been previously used. The return air grille [or grilles] need vacuumed off occasionally, as they are upstream from the filter. The $3 filter should be changed every 3 months [rule of thumb]....and most of them have a little white square on the cardboard frame to write install date.....and the arrow should point into the duct [if at filter grille]....or towards the furnace [if in ductwork slot]...or towards the blower [if in blower compartment]. My two cents.....
A house breathes just like you an I.For example every time your clothes dryer comes on it automatically creates a negative pressure inside the home.So if air goes out of the living area it has to be replaced.....now look above the ceiling fan ....you see the cover...underneath that is a hole straight to your attic....Now the stuff on your ceiling fan you call dust...call it insulation,rat fecies or anything else that is in your attic that could be pulled in your due to a negative pressure.
I had someone out to clean my ducts last weekend. He took a blue bag up in my attic. He came back down in just a few minutes and said I had mold and he even showed me a picture of something saying it was mold but I couldn’t really tell. I refused his service to take care of the mold. He went back up in the attic for a little while and then came down. I never heard any sounds that he was actually up there doing anything. How do I know if he actually cleaned the air ducts?
You should be aware that although a substance may look like mold, a positive determination of whether it is mold or not can be made only by an expert and may require laboratory analysis for final confirmation. For about $50, some microbiology laboratories can tell you whether a sample sent to them on a clear strip of sticky household tape is mold or simply a substance that resembles it.