Despite numerous attempts to develop a tool to measure the degree of intrinsic safety of a chemical process/product, intrinsic safety indices have not been widely used in industry for many reasons. Some indices are developed to evaluate the intrinsic safety of a given hazard, while others are more general and attempt to include the main hazards in a process. They all have different tradeoffs that motivate you to keep looking for a better metric. Below is a brief background on some of the indices reported in the literature. Table 1 shows previously developed indices, the parameters included in each of them, and their advantages and disadvantages. Dow's Fire & Explosion Index (F&EI) is widely used by industry as a measure of intrinsic safety, although it was not originally developed for that purpose, but to determine the need for fire protection. The index is calculated for selected units of the process as the product of a material factor (MF) and a process unit risk factor (PUHF). MF is a measure of the potential energy released by the material, as it takes into account reactivity and flammability. The PUHF is obtained as the product of the General Process Hazards (GPHs) penalty factor and the Special Process Hazards (SPHs) penalty factor. GPH is the sum of penalties due to the type of reaction/process, material handling and transfer, and chemical release control factors. SPHs are the sum of penalties due to chemical properties, hazardous process conditions, and the amount of hazardous chemicals in the unit1, 2. Additionally, Dow's F&EI and PUHF are combined to obtain the damage factor (DF), which is used to calculate the base Maximum Probable Property Damage (MPPD). Loss control credit factors are then taken into account... in the middle of the paper... re methylcarbamates. 5284962, 25.1994. Lapkin, M. Reducing Methyl Isocyanate Storage at the Rhone-Poulenc Plant in Institute, West Virginia; 26.1994. Waterfall; Environment; Federation, Management of Municipal Wastewater Treatment Plants (Practice Manual, No. 11). 6 ed.; McGraw-Hill: 27.2007. 29 CFR PSM of highly hazardous chemicals 1910.119.28. Aspentech ASPEN PLUS, available from: http://www.aspentech.com/: Boston, MA, USA, 2002.29. SimSci-Esscor; -Invensys PRO II, available at: http://www.simsci.com/products/proii.stm: Carlsbad, CA, USA.30. Hendershot, D.C., Conflicts and Decisions in the Search for Intrinsically Safer Process Options. Process Safety Progress 1995, 14, (1), 52-56.31. Surveillance of emergency events relating to dangerous substances, Annual Report 2005; U.S. Department of Health and Human Services; Agency for Toxic Substances and Disease Registry. .