In order to slow or prevent the growth of harmful food-borne bacteria, a refrigerator should be set to or below 40 degrees Fahrenheit. Meats, dairy products and vegetables can grow bacteria such as E. coli, salmonella and botulism if not stored at the proper temperature.
Using an appliance thermometer is the safest way to ensure that a refrigerator is set to the right temperature. Perishable food items bought from a grocery store should be placed in a refrigerator as soon as possible and should not be exposed to room temperatures for more than two hours. It is also important to make sure that a refrigerator is not tightly packed with food, as this can reduce the internal temperature and cause dangerous microorganisms to grow.