Introduction: Flammable dust particles when dispersed in air under certain conditions there is a risk of explosion. The aim of this study is determine the concentration of explosive dust, and the explosion risk assessment, in some a high risk industries of shahroud.

Methods: To determine the level of dust in factories investigated, sampling and determine the concentration based on the method NIOSH 0500 was done. Then to evaluate the igniter risk, risk assessment using Failure Mode Effects Analysis (FMEA) was conducted. The main sources of possible secondary explosion were determined by observation and interviews with managers and supervisors.

Results: Results of the survey the concentration of explosive dust in industries showed the most explosive dust generation, was related to the PVC industry with a concentration of 43 ± 74 mg per cubic meter. FMEA risk assessments results also showed that the cargo handling equipment, drying, cutting and drilling equipment, motors and switchgear lightning’s, are the most risky equipment in creating sparks and ignition. Also the study showed, silos with their high storage capacity can be the most likely sources of secondary explosions.

Conclusion: This study showed that concentration of explosive dust to a minimum explosive concentration is very low. But given the vast resources and great sources of ignition powder storage products that exist, pay attention to dust explosions in some of these industries is very important.