Most indoor air quality advice is written for a general audience and lands badly in Florida, where humidity dominates everything else. Here is the order that actually reflects this climate.
First: measure your humidity
Buy a hygrometer. Target 45 to 55 percent relative humidity. Consistently above 60 and you have conditions that support growth throughout the house, which no amount of filtration or duct cleaning will offset.
Second: find out where your system draws air
A leaking return in an attic or garage pulls that air into your house continuously. It is an ongoing source rather than a static one, and it is the single most under-diagnosed air quality problem in Florida homes.
Third: check for filter bypass
Air going around your filter rather than through it makes the MERV rating irrelevant. Check that the filter seats tightly on all four sides before spending money on a better one.
Fourth: look at the drain pan
Standing water in a condensate pan is the most common source of the smell people attribute to their ductwork. It is also easy to check.
Fifth: verify your exhaust fans work
Hold a tissue to the bathroom fan grille. If it does not hold, the fan is not controlling moisture. Then confirm the duct actually terminates outside rather than in the attic.
Sixth: then consider the ducts
Deliberately last. Duct condition matters, and degraded duct board shedding into the airstream is worth restoring. But fixing ducts while the house sits at 65 percent humidity solves the smaller half of the problem.
What we will not claim
That any of this resolves a health symptom. That is a question for a physician. We assess buildings and HVAC systems, and it is worth being clear about where that competence ends. See the full guide.
