# Chem Companion — Chemical Companion > Hazardous chemical decision support for first responders. (iPhone/iPad app by MEPSS LLC.) - Source: https://appshunter.io/ios/app/chem-companion/id1442599372 (this page in markdown: same URL + `.md`) - Developer: [MEPSS LLC](https://appshunter.io/developer/1442599371) - Category: Reference - Price: Free - Age rating: 17+ - Requires: iOS 15.0 · 103 MB - Released: 2018-11-21 - Data updated: 2026-06-10 - Monetization: free - User reviews in markdown: https://appshunter.io/ios/app/chem-companion/id1442599372/reviews.md ## What is Chem Companion? The Chemical Companion provides first responders with decision support for hazardous environments contaminated with chemical agents. This software tool is provided free-of-charge to the military, law enforcement, and fire departments. IMPORTANT: Access and usage of the application requires an approved account on chemicalcompanion.org . The account is free for first responders and military. Features include: - Detailed information on 3000+ common chemicals and synonyms - Personal Protective Equipment (PPE) including respirators - Hazardous Concentration Levels and Exposure Guidelines - Isolation and Protective Action Distances - ERG and Emergency Medical Information - Identify unknown chemicals using physical properties or exposure symptoms - Over 30 Decision Support Tools This application is only accessible by authorized personnel. You may register for an account at https://chemicalcompanion.org . ## Key features - Chemical information database - PPE recommendations - Hazardous concentration levels - Isolation and protective action distances - Emergency Medical Information - Chemical identification tools - Decision support tools ## Recent user reviews (3 of 3) All indexed reviews: https://appshunter.io/ios/app/chem-companion/id1442599372/reviews.md ### 1/5 — Will not work *2023-07-30* Crashes as soon as I open it ### 1/5 — Not usable *2023-03-15* Anytime I try to log in to the app, it just crashes on my iPad Pro. Tried deleting and reinstalling. ### 1/5 — Unusable *2022-08-31* Crashes any time you attempt to use any feature on latest iPad Pro ## Frequently asked questions about Chem Companion ### What is ERDSS? ERDSS is a chemical companion app that provides decision support for first responders in hazardous chemical environments. It offers detailed information on chemicals, personal protective equipment, and emergency response guidance. ### Is ERDSS free to use? Yes, ERDSS is provided free-of-charge to authorized military, law enforcement, and fire departments. Registration is required at https://chemicalcompanion.org. ### What devices does ERDSS support? ERDSS currently supports iPads. It is not available on other devices like iPhones or Android phones. ### How often is ERDSS updated? The latest version of ERDSS is 4.08.06, last updated on March 9, 2022. Updates provide new information and features to assist users. ### What kind of information does ERDSS provide on chemicals? ERDSS contains detailed information on over 3000 common chemicals, including synonyms, hazardous concentration levels, exposure guidelines, and emergency medical information. ### Can ERDSS help identify unknown chemicals? Yes, ERDSS includes tools to help identify unknown chemicals using their physical properties or observed exposure symptoms. ### What is the age rating for ERDSS? ERDSS has an age rating of 12+. This indicates the content is generally suitable for users aged 12 and older. ### Does ERDSS have ads? No, ERDSS does not contain advertisements. It is a free tool designed for professional use without commercial interruptions. ## Version history (last 5 releases) ### 5.0.3 — 2026-04-27 Critical performance fixes for chemical comparer, SCBA tool, and user feedback. Additional software improvements, organizational licensing, and data synchronization with chemicalcompanion.org. ### 4.08.06 — 2022-03-09 Added Gas Cylinder Recognition Tool. Added Fire Combustion Tool. Added Fire Extinguishment Tool. Added Skin Protection (PPE Selection) Tool. Added SCBA Entry Management Tool. Added Munitions Recognition Tool. Added Destruction Tool. Updated Emergency Response Guidebook Tool to the 2020 US and Australian versions. Updated/Added detector data in Detector Tool. Updated chemical data to incorporate additional threats and precursors. Addressed user feedback and general software errors. ### 4.07.02 — 2020-09-04 Addressed user feedback and general software errors. Added the Emergency Response Guidebook Tool including the 2016 US and 2018 Australian versions. Updated the Binary Reaction Tool to provide reverse calculation given a known Product/Gas. Added Radiation Shielding calculations to the Radiation Tool. Updated detector data in Detector Tool. Added ToxiRae Pro detector into the Detector Tool. Updated chemical data to incorporate additional threats and precursors. ### 4.07.01 — 2020-09-03 Addressed user feedback and general software errors. Added the Emergency Response Guidebook Tool including the 2016 US and 2018 Australian versions. Updated the Binary Reaction Tool to provide reverse calculation given a known Product/Gas. Added Radiation Shielding calculations to the Radiation Tool. Updated detector data in Detector Tool. Added ToxiRae Pro detector into the Detector Tool. Updated chemical data to incorporate additional threats and precursors. ### 4.07.00 — 2020-09-02 Added the Emergency Response Guidebook Tool including the 2016 US and 2018 Australian versions. Updated the Binary Reaction Tool to provide reverse calculation given a known Product/Gas. Added Radiation Shielding calculations to the Radiation Tool. Updated detector data in Detector Tool. Added ToxiRae Pro detector into the Detector Tool. 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Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-06-10.*