How to use COVID-19 qualifiers to determine the spatial overlap?

Time-space coincidence of epidemic situation: that is, you are in the same space with a confirmed case or asymptomatic infected person in COVID-19. This space refers to the same community, the same supermarket, the same station and the same airport in real life. If your mobile phone number and the confirmed case number stay in the same time grid (the range is 800 m * 800 m) for more than 10 minute, and the cumulative stay time of any mobile phone number in the last 14 days exceeds 30 hours, you will receive an epidemic prevention reminder message. This suggests that you may have had close contact with the confirmed patients and may be at risk of infection. But please don't panic, actively cooperate with nucleic acid detection to eliminate the risk of infection.