Humidity control and indoor air quality in Sharjah homes are shaped by the emirate’s coastal proximity, dense residential building stock, and year-round air conditioning demand. Left unmanaged, elevated indoor humidity creates conditions that degrade air quality, accelerate surface deterioration, and introduce microbial pressure that occupants rarely see until it becomes visible. This article explains how humidity and IAQ interact, what professional assessment reveals, and what Sharjah homeowners can do about it.