An ideal condition for mold growth in HVAC duct systems is high what?

High humidity creates an ideal condition for mold growth in HVAC duct systems. Mold thrives in environments where moisture levels are elevated because it requires water to grow and reproduce. When humidity levels are high, especially in conjunction with warm temperatures, the dampness can accumulate in the ductwork, providing a perfect breeding ground for mold spores.

While high temperatures can also contribute to mold growth, humidity is the more critical factor when it comes to moisture availability. Low ventilation may allow humidity levels to rise unchecked, but it is primarily the presence of humidity that facilitates mold proliferation in ducts. High pressure does not directly create conditions conducive to mold growth, and adequate ventilation typically helps to maintain lower humidity levels, reducing the risk of mold development.