Introduction: In recent years, dust storms frequently have occurred in large areas of the western half of Iran. Dust particles have negative effects on the environment and living animals, especially men's lives; hence, the current study was conducted with the aim of evaluation of airborne microorganisms and the concentrations of particulate and respirable matter causing from dust storm.

Materials & methods: This cross - sectional study was done in Ilam city (2012). For sampling and reading of TSP amounts used from direct reading devices in concentration range of 1µg/m3-2500 mg/m3. Cyclone was used for determination of respirable dusts with diameter less than ten microns. Also to determine microbial state of dusts used from the cellulose membrane filters (37 mm diameter). Finally, data were analyzed with spss software.

Findings: Results showed that the highest concentration of total suspended particles (TSP) and respirable particles (PM10) have been recorded in June with the amount of 22.5 and 1.3 mg per cubic meter. Comparison of Ilam air quality with standard values ​​( <150 μ g/m3) for respirable particles and total suspended particles showed that except in August that TSP concentration was below the standard value. In other months, the concentration of PM10 and total suspended particles were above the standard amount.

Discussion & conclusions: The results of this study showed that particulate concentration levels were higher than those of standard values and also contained microorganisms which can threaten human health; therefore, it seems necessary to control them.