Be honest: When was the last time you replaced the square package of baking soda that’s supposedly “freshening” your fridge? I probably rotate my tires more frequently than I rotate that baking soda—far from ideal. But there’s a better fridge-freshening method, and it doesn’t require baking soda at all.
Try charcoal, either in briquettes or activated charcoal pellets. The former is sold in the hardware-store bags you’d buy for a backyard grilling session. The latter can be found at pet shops and aquarium supply stores. ATK testing has found that both of these inexpensive nuggets actually trap and neutralize food odors better than baking soda—and their freshening power lasts at least a month.