Too little humidity can worsen the symptoms of a cold, infection, or respiratory condition. It can even dry your furniture out. But too much humidity will make your home uncomfortable and can increase the levels of mold and mildew in your home, which makes the indoor air quality suffer. If your home’s humidity levels are too high in the summer time, schedule air conditioner maintenance. If the humidity level is too low in the winter, add a humidifier to make your home more comfortable.