Over the weekend, at least 20 states saw a foot or more of snowfall, according to the New York Times—and even more experienced some combination of snow and ice. (In my neck of the woods, outside of New York City, we got 16 inches.) As snow accumulates around the perimeter of your house, one spot is as dangerous as an icy walk: snow-covered exhaust vents. Check that these three vents are clear of obstruction, especially after you shovel or snow blow, which could inadvertently cover them.