An article in the New York Times states that four hours is the maximum time that cooked meat should sit at room temperature. The USDA recommends two hours but cuts that to one hour when temperatures are over 90 F.
Bacteria grows and multiplies at temperatures from 41 F to 135 F, which is considered the "danger zone." Foods like salads and cold sandwiches require immediate refrigeration. To avoid food poisoning, perishable foods, such as meat, poultry, fish, dairy and eggs, should be discarded after four days of refrigeration because the bacteria that grows is undetected by taste, smell or appearance.