The danger zone temperature is the range of temperatures between 40°F and 140°F (4.4°C and 60°C) in which bacteria grow most rapidly. Bacteria can double in number in as little as 20 minutes within this temperature range, which is why it is called the danger zone. Leaving food in the danger zone for too long can cause bacteria to grow to dangerous levels that can cause illness. To prevent the growth of harmful pathogens, perishable foods should be kept above 140°F or below 40°F (greater than 60°C or less than 4°C) . Food should not be left out of refrigeration over 2 hours, and if the temperature is above 90°F, food should not be left out more than 1 hour. Safe food-handling practices, such as using approved methods to chill, heat, and store foods, are important to keep foods out of the danger zone and prevent foodborne illness.