At a recent live pop concert in Tokyo's Chiyoda Ward, the large screen set up at the edge of the stage didn't give the audience a close-up view of the idol or any other eye-catching visual. Instead, it changed colors to show the carbon dioxide (CO2) level in the air, in an unconventional effort to contain the spread of COVID-19. During her performance, a pop star on the stage watched the screen and said the CO2 concentration “appears green, which means this live concert is peaceful.” Her comment drew laughter from the spectators.

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