Indoor air quality in a humid South Florida home

1. Measure humidity

An inexpensive hygrometer tells you where you are. The EPA recommends keeping indoor relative humidity below 60%, ideally between 30% and 50% (EPA mold guide). Many South Florida homes sit higher than that even with the AC running.

2. Fix the causes first

• Thermostat fan on Auto, not On.
• Right-sized AC. An oversized system shuts off before it dehumidifies.
• Sealed return ducts. Leaky returns pull humid attic air into the house.
• Bath and kitchen exhausts that vent outside, not into the attic.
• Plumbing and roof leaks fixed promptly.

3. Then consider equipment

• Whole-home dehumidifier, if humidity is still high once the causes are fixed.
• Better filtration: a MERV 11–13 media filter, sized so it doesn't choke the blower.
• UV light at the coil to limit growth on the coil and in the drain pan.
• Variable-speed equipment at replacement time, for long, slow, dehumidifying cycles.

Be wary of devices that make big claims. Ozone generators sold as air cleaners can harm the lungs, and the EPA advises against them (EPA on ozone generators). For many "ionizing" products, independent evidence is thin.

4. Ducts

Cleaning helps when there's visible mold, pests or real debris; it isn't a routine yearly need (EPA on duct cleaning). Sealing leaks usually matters more. See duct cleaning and repair.