Perishable foods should not be left out for more than two hours. After this, foods should be refrigerated or thrown in the trash. Otherwise, harmful bacteria may start growing.
If the temperature of the room is very warm or the food is outside on a hot day, perishables should be refrigerated after one hour to prevent food-borne illness. Salmonella is one of the most common bacteria that cause "food poisoning." In fact, other food-related illnesses have decreased since the beginning of the 21st century, but this is not the case with salmonella. The symptoms caused by this bacteria usually last 4 to 7 days, but some cases require hospitalization.