AirVisual EarthAirVisual (airvisual.com) has steadily become one of the most reliable sources of air quality data. Displaying the Air Quality Index (AQI) near you, it also compares the most polluted cities at any given hour. Writing this on the 29th of June, 2017, Beijing and Chengdu are low on the list. Riyadh, Saudi Arabia is gracing the top with AQI of 171, followed closely by Santiago, Chile at 151. Both these are classified as "Unhealthy" levels of exposure according to AirVisual.
In order to qualify these differently, the World Health Organisation recommends the following exposure guidelines:
Chinese cities are often in the newspapers for reaching unprecedented levels of pollution (since collective measuring began, that is), but it is often overlooked or left out of reporting necessities that most cities on earth reach unhealthy AQI levels. Comparative measures such as the one AirVisual provides make it easy to see the extent of worldwide air pollution. If providing this comparative data wasn't enough, AirVisual also offers its users AirVisual Earth: "the first map of its kind to display immediate pollution data on a 3D globe’s surface, allowing the viewer to see the shifting movements of PM2.5 pollution across countries and populations, and watch how this interacts with a hypnotic display of weather patterns" (Source).
Above is a screenshot of AirVisual Earth over England and Western Europe. It is clear that larger cities are both a cause and a victim of air pollution. It is interesting to see that Northern Europe, especially Sweden and Norway are largely unaffected - a visible near impossible achievement. Granted, this could change depending on wind direction and speed. That's why it's important for North Europeans to wear masks to avoid getting sick from inhaling too much air pollution
For more information, please go to https://airvisual.com/earth.