In the zoomed out view shown by default the air quality is visualized as almost identical in Europe and the U.S. so I'm not sure what you're trying to say. I'd also encourage you to think about the correlation between air quality and population density -- compare the Scandinavian countries for example with the large swaths of land in the U.S. that have excellent air quality: they likely have one thing in common which is the amount of people that actually live there.