For reference, this is the site I found that went back farther. Milan is not constant days of 150, as Hubei is. That said, it is littered with many high value days. Contrasted with Seattle, which has been steady below 60 for the time period.
Take this over to Australia [below], and you can see that even they had terrible air as recently as mid January.
Contrast to Norway [also below], which has hovered on fine air quality for the entire time. Same for Japan, all told.
Basically, the worse your air quality, the more severe cases you are seeing. To a marked degree.
Edit: Just eyeballing, Milan is worse than Seoul. Agreed not as bad as Hubei. But between.
And again, China was worse. Italy is just worse than all places I checked that had a lot of cases, but not as many severe cases.