Pollution index and air quality table

(1) As can be seen from the table data, the quality grade of Nanchang is Grade III, and the air quality is the worst.

(2) The air pollution index of Lushan Mountain is: 25, and the comparison table ①25 is between 1-50. In this range, the quality is good and the level is first-class. The primary air pollutant in Jingdezhen is sulfur dioxide.

So the answer is: (1) Nanchang; (2) I am excellent; So 2.