The atmospheric diffusion parameters in the Dachang area of Nanjing are calculated using tatroon data under breeze conditions and compared with those in the city of Lanzhou. Calculation is also performed of khe SO₂ instantaneous concentration distr ibution in the area under breeze and calm conditions with two sets of formulas of point source and area source respectively. It is found that some places in the area are subject to pollution. This provides useful criteria for construction planning and environmental protection in the area.