The reality of multiple cities carrying high levels of pollution is known. It could be radically solved using electric energy coming from clean sources, although this still seems arriving late. In the same city there are different spots with very noticeable differences in terms of pollution. The advice is to seek for those with less or have a method to avoid it even in the worst zones.
As of today there are buildings with special filters that provide clean air to the structure. Also different projects that focus chemical reactions done by structures inside the city, for the exterior.
Those that point the public air should remember the necessity of a filtration rate that is relevant taking into account the quantity of machines producing the pollution. A rather complicated task.
However, this is not impossible and specially having an almost unlimited source of power in the nearest star and the ability to use natural solutions like vegetation, with multiple examples of very complex purification capabilities.
The human civilization should get rid of the pollution in cities with a method. Finally forms of filtering first and to eliminate the sources. Instead of waiting for worse times and while the history writes pages where multiple individuals were sharing their existential space with very dirty particles that promote indubitable health problems.
Strange, but today to find air filtering projects in a serious scale looks difficult. Not those images of cities with high levels of pollution.