As the air flows through the supply and return ducts of a building, dust particles can
drop out of the air stream and collect on the inside of the ductwork. Given enough time
and enough dust, the build-up can become a problem. Under the right conditions, bacteria,
dust mites,and mold and mildew spores can collect in the dust then become airborn again.
Even people who are not sensitive or allergic to these contaminants can have a reaction
when exposure is too intense.
Proper cleansing of the air with good filters and ultra-violet light can help to reduce
problems and greatly improve the air quality.
When attempts to improve air quality are not sufficient, it may be necessary to have the
ducts professionally cleaned. With the help of a powerful vacuum machine and air pessure,
technicians can blast the dirt free and collect it in hepa filters. Occasionally chemical
cleaners will be sprayed into the grill openings to loosen clumps of dirt that don't free
up with the air movement.
Under the most extreme conditions of "sick building syndrome", the ductwork has
to be replaced.