Air Duct Cleaning
Carl Grimes, Environmental Specialist says: "There are two professional standards widely accepted and very good. Each organization has lists of members on their web site so you can find someone in your area. Then, as others have said, check them out because being a member doesn't automatically mean they are honest. Its a good starting point however.
Go to www.nadca.com or www.acca.org
A word of caution for those with chemical intolerance concerns. The standards do not prohibit the use of chemical products. So tell them, No chemicals! Of any kind. If they don't agree in writing don't hire them. Keep looking until you find someone who will respect your requests.
The only way to sufficiently clean, without cross-contaminating a house, is with a BIG truck as the vacuum source! Portable HEPA vacs should only be used if the exhaust is directly into the outdoors."