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This work was developed using a structured method rather than a fortuitous observation. During a standard workday (from 9 AM to 6 PM), I recorded the sound of pollution—specifically, the noise produced by an air purifier on a typical day in Beijing. For this, I used the Air Quality Index (AQI) scale as a reference. The AQI converts the concentration of various air pollutants into a standard scale, typically ranging from 0 to 500. Every hour, for eight hours, I paused to check the current index. The recorded AQI value determined the duration of each recording: for example, if at 2 PM the AQI was 154, I recorded 154 seconds of both sound and image of the air purifier. At the end of the day, I overlaid all the collected videos, setting the maximum duration based on the highest AQI recorded during the period—174 AQI, resulting in a final video of 174 seconds.