I just had my Air ducts “cleaned”. The person who came to my house works for an air duct cleaning company who uses a professional vacuum. He said the company would charge me about $900 but he can do it aside on his own and charge me half of that. However, when he came over the house, he brought the rotary brush along with his domestic vacuum cleaner that it’s hose was about 5 feet long, I ask him that the wasnt strong enough to pull dust out, and he said, it’s similar to what companies use. I was in doubt and he didnt cover the vents so im thinking all dust must have come out from every air vents. Could this vacuum have taking the debris out of the air ducts? Or how can I myself find out if the inside of the air ducts have been cleaned and no debris is sitting there? I have dust all over my house.
I was with you until you said avoid steaming cleaning or moisture, there is no way you can remove mold or any other type of biological without moisture. The best way to do this is in fact with a steamer using a commercial disinfectant and a non reactive odor remover so your home smells refreshed and not like a hospital . This is directly contradictory to your article.

Compared to using a duster or changing out air filters, professional duct cleaning means going through all the many elements of the HVAC system. This includes, but is not limited to, the supply and return air ducts, grilles, diffusers, exchangers, heating & cooling coils, drip pans, fans and the air handling unit. Keeping these maintained means avoid problems like pollen, mold or overt dust buildup. This is definitely a problem you want to avoid.
A study done by U.S. Environmental Protection Agency researchers measured dust levels and HVAC system efficiency in test homes during a one-week period during the cooling season and found duct cleaning did not significantly improve dust levels or system performance. Based on that report and other independent research, the EPA’s official advisory on duct cleaning concludes:

I bought a Groupon and initially had to wait 5 weeks for them to make an appointment. I took the day off of work and they called 40 min prior to their scheduled time to let me know they had to reschedule as someone didn't show up for their shift that day. I then was scheduled 5 more weeks out and they called today to also reschedule that appointment, another 4 weeks out. I cannot speak of their work as their lack of professionalism has made me consult Groupon to get my money back however as I read the reviews this seems to be a theme with this company!
Chemical biocides are regulated by EPA under Federal pesticide law. A product must be registered by EPA for a specific use before it can be legally used for that purpose. The specific use(s) must appear on the pesticide (e.g., biocide) label, along with other important information. It is a violation of federal law to use a pesticide product in any manner inconsistent with the label directions.
For more than 60 years Stanley Steemer has been perfecting our hot water extraction method to clean carpet with unparalleled results. Take control of the environment in your home and enjoy a cleaner, healthier living space for your family. Every carpet cleaning is proven to remove an average of 94% of common household allergens. We remove the dirt you can see and the allergens you can't. 
The renters in my rental home complained of the dryer needing 2 cycles to dry their clothes. I called out Arizona Air Duct to clean the vent. Well, $75 later the issue is not fixed. I had another company come out. They pulled out a section of the vent to show me- there's maybe half the piping still coated in lint. (I wish i could post pictures here...)
My vent covers have lots of mildew. They look bad! I live in a very humid climate in a condo. The handyman here has offered to take those down, wash them, sand, & then spray paint them with a mildew resistant paint. He said that he will leave them off overnight to dry. I am wondering if this is safe to breath the AC blowing out into the open all night??. ! Guess it is better than the mildew!?
If no one in your household suffers from allergies or unexplained symptoms or illnesses and if, after a visual inspection of the inside of the ducts, you see no indication that your air ducts are contaminated with large deposits of dust or mold (no musty odor or visible mold growth), having your air ducts cleaned is probably unnecessary. It is normal for the return registers to get dusty as dust-laden air is pulled through the grate. This does not indicate that your air ducts are contaminated with heavy deposits of dust or debris; the registers can be easily vacuumed or removed and cleaned.
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