i predict #2-3 to be BJ and SZ.

air quality is 1 factor, but there are others also crucial to life expectancy, medical care as the most.

HK dosen't have a great air, rarely sees blue sky and clouds, yet it ranks near the top of the world on life longetivity.

recently i went back to china, to my surprise among 3 palces i visited, only BJ had blue sky