Colds are generally contagious to others within 1 meter of each other and less likely to be contagious beyond that. If it is influenza, it is a more common infectious disease. The main way of transmission is respiratory transmission, i.e., through the people carrying influenza virus, the droplets carrying influenza virus, into the respiratory tract of the uninfected people, the formation of the spread of influenza. Therefore, infection can generally occur within 1 meter, and the possibility of infection after exceeding 1 meter is relatively small. Because the distance that respiratory droplets can reach is relatively short, especially the distance of 2~3 meters is relatively rare. And droplets generally float downward in the air, it is difficult to enter the respiratory tract after a long distance, thus causing the probability of influenza transmission is even smaller.