It doesn't feel like its a problem because of two reasons:
1. Pollution and CO2 emissions are two separate issues. The US has strong pollution regulations regarding pollution near large populations, so even if it contributes to the green house gas problem for people living in cities air quality is good.
2. The US was previously the global leader in pollution by a wide margin, producing 300x what Brazil produced for instance in 1950. In recent decades, manufacturing in the US has become cleaner bit by bit, so there has been improvement. This is unfortunately dwarfed by the quality of Europe where pollution was always a lesser problem, and environmental guidelines became more stringent faster than in the US.
Many people like to compare the US to Europe, and in that respect the US usually looks terrible but the US isn't Europe and has never been in the same place socioeconomically. It is better to compare the US to China or India, because in geopolitics we are in the same place---large manufacturing nation, large population, large geography, former colony, quasi-imperial ambitions.
[1] https://en.wikipedia.org/wiki/List_of_countries_by_carbon_di...
https://wri.org/blog/2014/11/6-graphs-explain-world%E2%80%99...
Last time I checked as a nation we are working hard to reduce emissions have some of the lowest in the world. Perhaps it would be more useful to go and bash China and India, two countries in which seeing a clear sky in a large city is a rarity.