To give you a sense of scale, there’s a big controversy in Utah right now because the PM2.5 air pollution in Salt Lake City has sometimes hit as high as 69. That number is considered unhealthy. According to the Environmental Protection Agency, even adults should avoid all outdoor activities if the count hits 300. In Beijing and other Chinese cities, the air pollution rating can spend days hovering around 500.
At this point I’m not sure we can call it “air” anymore.