Abstract: With the classification method of atmospheric stability in RG 1.23, the application of stability category G in relative concentration calculation by PAVAN for inland site with low wind speed and more static wind frequency are discussed. The analysis shows that the relative concentration resulting from the RG 1.23 method is about half of that from HAD 101/02, in which atmospheric stability is determined by the temperature gradient and the wind speed but does not include category G. Since the RG 1.23 atmospheric stability classification method is more precise in the classification of stable weather, it’s more effective and reasonable to use the classification of stability in RG 1.23 than that in HAD 101/02 in the input file for PAVAN code while dealing with the inland site with low wind speed and more static wind frequency.

Key words: calm condition, stability class, relative concentration, PAVAN