When I first arrived in China I kept a large supply of n95 masks for those days when the PM2.5 AQI was dangerously high, that way I could keep running while apparently reducing the risk of damage to my lungs. Like many I also had one for biking in traffic in Taiwan which came with removable filters, and cheaper disposal ones in case I was sick or had to spend any time in a hospital. As would be expected when I shared this photo of me prepping for a run in my room in Fuzhou, it was met with a much stronger reaction than it would today.

Incidentally, air pollution in China today, though still considered unhealthy, is a far cry from when I was there. I bet in some places you might even be able to see the sky.