Over the last few months, you may have heard about China's growing smog problem. In Beijing, Shanghai, and many other areas of China, the smog is so bad that the air quality index (AQI) has started spiking over 400, and sometimes reaching 500 -- the top of the AQI scale. Just for some context, an AQI above 100 is generally considered unhealthy -- over 300, and we're talking about a serious hazard to health (i.e. it can be lethal). To better illustrate the scale of China's smog problem, NASA has captured an image of China's northeastern seaboard that shows just how bad China's smog problem really is.