Humidity near the lake, limestone dust and cedar
Being near the water adds moisture to the air, especially on calm summer evenings, and the surrounding Hill Country brings its own dust. Limestone soil is chalky, and grading or building nearby sends fine white powder into the wind. Ashe juniper, locally called cedar, is also common on the hills and releases pollen in winter.
The combination matters for ducts. Warm humid air meeting a cold duct can cause condensation, and condensation plus dust is a good place for growth to begin. Rooms with long duct runs or little airflow are the usual trouble spots, so we look at those first.

