My coworker went there last year. When the factories were on he couldn’t see the hotel adjacent to his. When they were shut down it was almost crystal clear with blue sky. Reminded me of a distopian SciFi movie like Bladerunner or Johnny Pneumonic.

On the other hand, other Asian countries are throwing tons of money at the problem.

It's not that easy though because you need to take the chemistry into account. Some pollutants react distructively with others, so if you reduce those first you'll get more pollution than before. Oops. (China is in that situation, for example.)