Press the home button and the on / off button ( top right edge ) simultaneously to take a screenshot of whatever you see on the device .
同时按下主键和开关键（右上角），就可以对你在设备上看到的任何图片截屏了。
On the day this screenshot was taken beijing was actually enjoying a rare blue sky day - hence the person in the upper right-hand corner is not wearing the white surgeon 's mask that he dons on more polluted days .
Here 's a screenshot from one of the most popular pollution apps , which includes a chart of pollution levels over the last 24 hours and the last month .
