A triangular arrow is printed on the bottom of the takeaway plastic box, and the number in the box is 5, indicating that the box is made of PP (polypropylene), and the plastic box made of this material can be heated by microwave oven. The heating time is 3-5 minutes, and the time should be adjusted according to the type of food and the purpose of heating. Plastic boxes, plastic wrap or other special containers that can be heated by microwave oven are also used when heating food to prevent food from overflowing. Even food-grade plastic containers will release a lot of microplastics and nano-plastic particles when heated in the microwave oven. For the sake of health, it is best to avoid heating the plastic container 4 in the microwave oven.