I live in the Chicago area. Have the same issue. The musty smell is just high humidity. A dehumidifier will do wonders. Usually we notice the smell is gone in 4 - 8 hours after we turn on dehu. If the smell is sewer gas, try pouring a few cups down your basement/cellar drain. When it is dry, the trap can dry up letting in sewer gas. Check out my writing on http://www.WebsterInfo.com