In 1972, Arm & Hammer launched an advertising campaign promoting the idea that a box of baking soda in the refrigerator could control odors.[4] The campaign is considered a classic of marketing, leading within a year to more than half of American refrigerators containing a box of baking soda.[5][6] This claim has often been repeated since then.[7][8] However, there is little evidence that it is effective in this application.[9][10] Arm & Hammer further claims that the box must be replaced monthly.[11]