According to a recent Duke University study, mold growth appears to be linked to dewpoint conditions rather than the relative humidity. Researchers found that sustained mold growth could occur when wet conditions were produced through condensation, as the air is cooled past its dew point.

It is important to note, how- ever, that condensation is not the only source of water in an HVAC system. It can occur as a result of water carryover due to faulty coil design, dirty coils, or failure of the drain pan to operate properly, or improperly operating humidifiers.