Erm, no. I don't know where you got your information from... even the sources from Chinese says you are incorrect.
You can check them all here:
Result for the first half of 2013:
Air in focus cities
(Includes Beijing and Tianjin)
31% of the days are normal air quality, average is 54.8%.
26.2% of the days are heavily polluted, average is 10.3%.
- Average PM 2.5 in Beijing was 103 ug/m^3, exceeds 1.9x, only 38.9% of the days w/normal air quality
- Average PM 2.5 in Tianjin was 102 ug/m^3, exceeds 1.9x, only 36.5% of the days w/normal air quality
If we include other largest cities the equation:
- Average PM 2.5 in Shanghai was 66 ug/m^3, exceeds 0.9x
- Average PM 2.5 in Guangzhou was 54 ug/m^3, exceeds 0.5x
The north you go the worst it gets. The more industrialized you are, the worse it is. Tianjin is not just a commercialized city, it's also heavily industrialized. It may not be as worse as it's nearby Shijiazhuang, but it's no where near moderate