Studies have shown that indoor air can be 2 to 5 times MORE polluted
than outside air. Most disposable filters remove about 10% of these
pollutants allowing 90% to enter the air system, even during the
construction of a new home. The pollutants contain dust, pollen, mold
spores, animal dander and much more. These materials collect in the
furnace, air conditioner and duct surfaces, just as they do on the
furniture and floor surfaces. The furniture and floor are cleaned
regularly but the duct surfaces are hidden from view and can only be
reached by specialized duct cleaning equipment. These pollutants can
migrate out into the room again, or become a food source for mold and
bacteria, which can thrive in this dark comfortable environment from
high humidity or moisture from the air conditioner or humidifiers.
Biological growth can release mold spores or toxins into the air system.
How can mold grow in a duct system and what problems can it cause?
Mold spores require a stable temperature, a food source and moisture
to live and reproduce. Dust and dirt that go through the filter are a
good food source. The furnace/air conditioner is designed to maintain a
comfortable temperature, and moisture is available from humid conditions
in the environment, the humidifier in the furnace or the cooling coils
in an air conditioner. Live molds can release spores that will trigger
allergic or asthmatic reactions, sometimes severe, in about 10% of the
population. Mold both living and dead can produce toxins that may cause
short term allergic reactions. Long term exposures to low levels of some
mold toxins can result in permanent chemical sensitivity to common
compounds in the environment.
How Should the Air System Be Cleaned?
Air system cleaning is a simple four step process. To view the details of this process, please view our cleaning procedures page.
Will a dirty air system result in higher energy costs?
Depending on the amount of contamination and its location, energy
consumption could be increased. If the fan blades, evaporator coil or
other control components of the system are heavily contaminated, the
system may have to run much longer to cool or heat the occupied space,
wasing a lot of energy.
Which parts of the air system should be cleaned?
There are 3 major parts to an air system: 1. The supply and return
grills; 2. The interior surfaces of the supply and return vents; and 3.
The furnace/air conditioner air handler. All 3 components must be
cleaned. If only one or two of the components are cleaned, the
contaminates from the 3rd component will rapidly contaminate the ones
that were cleaned.
How often should I have my air ducts cleaned?
Once an air system is thoroughly cleaned, it should remain clean for
3 to 7 years if properly maintained and a high arrestance filter is
installed. A standard disposable filter only stops about 10% of the
airborne contaminates, allowing 90% of the dust in the room to flow back
into the air system. To maintain protection against biological growth,
an EPA registered biocide should be applied every 6 to 12 months by a
qualified Duct Cleaning Professional.
What are the sources of air duct contamination?
All inside air was once outside air, so all of the dust, chemicals,
pollen, insects and mold spores in the ouside air can be pulled into the
air system. People shed millions of tiny dead skin cells every hour.
Cooking smoke, household insect sprays, personal care products are also a
source of pollutants. Many construction materials, carpets, wood
products and plastics give off pollutants as well. During construction
or remodeling activities, many types of dust are produced and find their
way into the duct work. If the duct components were stored outside
prior to construction, they may have collected dust, rain water and even
mold before they were installed in a system.
What does it cost to have a whole air system cleaned?
This can depend on a lot of factors, such as the size of the home,
the number of supply ducts, how long since the ducts were cleaned, etc.
The whole system should be cleaned and a more efficient filter installed
to keep the system clean longer. A competent duct cleaning company
would not be able to do this for less than $200 for a small home or $800
for a large home.
