Why does the nucleic acid of Chongqing health code pop-up window turn green in less than 20 minutes?

Received nucleic acid sampling information. Chongqing, referred to as Mountain City and Fog City for short, is a provincial administrative region and municipality directly under the Central Government of People's Republic of China (PRC). The health code of this city is called Yukon code. After receiving the nucleic acid sampling information, the health code turns green in less than 20 minutes. The green code is the certificate of returning to work during the epidemic period, which is universal and mutually recognized in the whole province.