The presence of moderate to severe mould infestation is usually accompanied by a musty or mildew odour. Visual inspection can help to identify the presence of mould, noticeable through the growth of black or white spores around the vents and inside the ducts.
Whether or not you decide to have the air ducts in your facilities cleaned, committing to a good preventive maintenance programme is essential to minimise duct contamination.
To prevent dirt from entering the system:
Use the highest efficiency air filter recommended by the manufacturer of your heating and cooling system.
Change filters regularly.
If your filters become clogged, change them more frequently.
Be sure you do not have any missing filters and that air cannot bypass filters through gaps around the filter holder.
When having your heating and cooling system maintained or checked for other reasons, be sure to ask the service provider to clean cooling coils and drain pans.
During construction or renovation work that produces dust in your premises, seal off supply and r eturn registers and do not operate the heating and cooling system until after cle aning up the dust.
Remove dust and vacuum regularly. (Use a high efficiency vacuum (HEPA) cleaner or the highest efficiency filter bags your vacuum cleaner can take. Vacuuming can increase the amount of dust in the air during and after vacuuming as well as in y our ducts).
If your heating system includes induct humidification equipment, be sure to operate and maintain the humidifier strictly as recommended by the manufacturer.
Source: EPA United States Environmental Protection Agency