Did you know mold causes symptoms of tiredness and sinus congestion? Did you know window sills are the top breeding ground for microscopic mold? Here is a fix: give your window sills a weekly shower with a solution of one part bleach to four parts water in a spray bottle. Let it sit for about an hour then wipe. Other places to shower are refrigerator seals, bathroom air vents, and under the kitchen sink which also harbor mold.