The picture below shows in color the concentration of air pollution in North America. The lower US seems to have three notable pollution sources according to the color scale shown in the lower left of the photo. Roughly locating these three sources would be in California in the Western US, Chicago area in the Great Lakes region, and Baltimore to Boston along the I 95 corridor.
Now for a look at Asia and the middle East.
According to these maps, the above one shows where most of the air pollution originates.
The following from the Science website is some information about these pictures. While the text is from November last year, the picture map shows the situation in real time. These are for July 16, 2017.
By Dennis NormileNov. 28, 2016 , 3:15 PM
China’s air is notoriously toxic: Each year, it contributes to the premature deaths of some 1.6 million people. Concerned about how such pollution was affecting his family, Beijing-based data scientist Yann Boquillod founded AirVisual Earth, an online air pollution map that uses data from satellites and more than 8000 monitoring stations to display global air pollution in real time. The AirVisual Earth interactive maps prevailing wind patterns and shows color-coded concentrations of PM2.5—airborne particulate matter less than 2.5 microns in diameter that can penetrate deep into the lungs. Users can zoom in, tilt, and spin the globe for better viewing. The air pollution visualization was crafted “so people really understand how bad it is,” says Boquillod, who hopes an informed citizenry will pressure governments and communities to clear the air. AirVisual also delivers 3-day air pollution forecasts for 6000 cities to smartphones, and it recently began selling low-cost monitors people can use to track indoor and outdoor air pollution. “People want to share that data,” Boquillod says.
The pictures are screen captures. You will have to go to the Science site link here to move around the globe.
I am not a fan of the 2.5micron particles stuff. Another study suggest that there is no evidence for it being considered a vehicle for killing massive numbers of people. See Junk Science links to see why I say that. This is a good map for chasing black carbon and other aerosols.