Iran Occupational Health

Abstract
Background and aims: Road transportation of chemicals due to occurring various accidents and their hazardous consequences has high importance. The aim of this study was to determine safe distance in the accidents of road transportation of toxic chemicals in order to use in emergency response planning.
Methods: In this study, firstly, transportable chemicals -by road- were studied and ammonia, chlorine, 1,3-butadiene, benzene and toluene were selected for further study and modeling of toxic materials releases. Next, chemical exposure index (CEI) was determined and hazard ranking was done. Finally, modeling of toxic substances releases was done using ALOHA and PHAST software's.
Results: The results showed that, using the CEI index, ammonia, chlorine and 1,3-butadiene with exposure indexes of 597, 548 and 284, respectively, have high importance and need further investigation. In the final assessment that was done according to ERPG-3 concentration, using ALOHA software, ammonia with 2800 meters, and using PHAST software, chlorine with 3004 meters, have the highest hazard distances.
Conclusion: Assessment of the results showed that the used softwares and the CEI index don^'t have the capability to provide correct results at low concentrations (ERPG-1 & 2). Due to difference of the results using PHAST and ALOHA softwares, and CEI index, it is recommended to use the highest hazard distance-obtained by ERPG-3-for emergency response planning, without paying attention to type of the material and type of the softwares.