For example, Zhengzhou epidemic prevention and control headquarters: this should be judged according to the situation. If you go out on business, you are not in Zhengzhou, and you can't go back to Zhengzhou, the code won't turn red.
However, people who go out should do their own nucleic acid testing in China. If the health code changes color (such as yellow), nucleic acid detection proves that it can be used as a material to adjust the color of the health code in the later stage.
Whether the health code will change color is related to the holder's travel location. If the travel location belongs to the risk area, the health code will turn yellow. If the travel place does not belong to the risk area, the health code will not change color, but it will change color if it is positive through nucleic acid detection.