Human can live without food and water for many days but they can not live without breathing Air more than a few minutes. Then, Air Pollution is a Problem that additional must attended. Many countries have developed search work and Programs to Control air pollution. There are a lot of industrial activities that lead to the trace element and particles in the air in Yazd city. This study was descriptive and Cross- Sectional. The amount of dust fall in the Air of Yazd was determined and also the amount of arsenic in dust fall was determined. In this study, The Sampling was done from 30 August 2009 to 10 March 2010 at four 1 month's Periods in Jomhuri bulvard, Homafar Square , Shahid Behesti Square , Seyd GoleSorkh Ave , and Aiatollah kashani Street by Jar method. The amount of Arsenic was determined by graphite furnace atomic absorption. The Maximum mean of Arsenic in dust fall was in the second Period equal to 10.677±3.133 μg/kg and the minimum mean of Arsenic was in the Fourth Period equal to 3.066 ±1.205 μg/kg. The maximum value was related to Jumhori Eslamic Bolvard equal to 15 .086 μg/kg and the minimum value was related to shahid Beheshti square equal to 1.134μg/kg. Discussion: Comparison of means the P-value=.062 for different periods and the P-value=.389 for different station was obtained .These was shown that there is no meaningful difference between the Arsenic value in different periods and station. The maximum value of arsenic was observed in the second period of sampling, which is related to enhancement of traffic in city and decrease of air humidity. In addition, the maximum value was in Jumhori Eslamic Bolvard station that is due to existence of industrial factories of in these areas.