Know Your Chemicals app - user guide

A user guide for the NPSA Know Your Chemicals app - a secure mobile tool for UK emergency services staff to identify chemicals of concern, including HME precursors and poisons.

Last Updated: 14 July 2026

What is the Know Your Chemicals app?

Know Your Chemicals app symbolThe Know Your Chemicals (KYC) app is a secure mobile reference tool developed by the National Protective Security Authority (NPSA). It helps emergency services personnel and government staff identify and learn about chemicals that could be used to make homemade explosives (HME), chemical agents, or poisons.

The app is classified at OFFICIAL level. It is only available to authorised users with an approved work email address.

The app replaces all previous printed Know Your Chemicals guidance, including the booklet and aide memoire. Those printed products are now out of date. Staff should securely destroy any copies they hold.

Who can use the Know Your Chemicals app?

The app is available to:

  • All UK emergency services personnel, particularly those in operational roles
  • UK government employees whose work directly relates to hazardous chemicals, homemade explosives, or other dangerous materials

NPSA recommends that all operational emergency services staff have access to the app, so they have an identification tool available when on duty.

Access is restricted to approved email domains. Users must verify their account regularly to maintain access.

What information does the app contain?

The app contains a database of chemicals of concern, including precursors to homemade explosives, chemical agents, and poisons. Each chemical entry includes:

  • Physical form, colour, and odour
  • Associated hazards
  • Legitimate uses

Please note: This list is not exhaustive. Many chemicals could potentially be used in the manufacture of harmful materials, and users should bear this in mind.

Additional features

Log - Users can add multiple chemicals to a log at a scene. This helps track complex incidents and makes it easier to share relevant information with others. Users can record where a chemical was found, its concentration, and quantity if known.

Learning - The app includes a dedicated learning section covering:

  • Legislation that restricts access to chemicals of concern
  • Hazard symbols and their meanings
  • Examples of clandestine laboratories and indicators of illicit manufacture
  • Educational videos demonstrating illicit chemicals at a scene

How to download the Know Your Chemicals app

  1. Download the app from the Google Play Store, Apple App Store, or your organisation's internal IT app system.
  2. Install the app onto your work-issued device where possible.
  3. When prompted, enter your work email address to verify your identity.
  4. You will receive a verification code by email. Check your junk folder if it does not appear in your inbox. Enter the code promptly, as it is time-limited.
  5. If your organisation's firewall blocks the verification email, use the alternative verification method shown in the app.
App Store logoKYC App QR Code - App Store
Google Play logoKYC App QR Code - Google Store

 

How to use the Know Your Chemicals app

The app is a reference tool to support chemical identification. It is not a decision-making tool and does not provide operational advice.

Use the app to:

  • Identify specific chemicals of concern at a scene
  • Access reference information about hazardous materials
  • Log chemicals found at a scene for information sharing purposes

Do not use the app to:

  • Replace any part of your service's existing procedures
  • Make decisions about how to manage a scene
  • Substitute for expert advice — always consult a specialist when hazardous chemicals are suspected

Each service is responsible for determining how the app fits within its existing protocols, and for ensuring staff know the correct procedures to follow.

Acceptable use and data security

This app is classified at OFFICIAL. Misuse may result in access being removed by NPSA.

You must not:

  • Share app content with anyone outside of the emergency services or approved government departments
  • Reproduce or publish any content from the app, in whole or in part
  • Retain the app once it is no longer required for your role
  • Use the app for any purpose outside of your professional role

You should:

  • Only download the app onto a work-issued device where available
  • Delete the app and all associated data from your device when it is no longer needed

Please note: This app is subject to user analytics, which are reported to NPSA.

Frequently asked questions (FAQs)

The Know Your Chemicals (KYC) app is a secure mobile reference tool developed by the National Protective Security Authority (NPSA). It helps authorised UK emergency services staff and government employees identify chemicals that could be used to make homemade explosives, chemical agents, or poisons.

The app is available to UK emergency services personnel and government staff whose work relates to hazardous chemicals or homemade explosives. Access is restricted to those with an approved work email address.

The app can be downloaded from the Google Play Store, the Apple App Store, or your organisation's internal IT app system. It should be installed on a work-issued device where possible.

The app contains a database of chemicals of concern, including precursors to homemade explosives, chemical agents, and poisons. Each entry includes details on form, colour, odour, hazards, and legitimate uses. The list is not exhaustive.

No. The app is a reference tool only. It does not provide operational advice or replace expert guidance. Users should always consult a specialist when hazardous chemicals are suspected at a scene.

The Know Your Chemicals app has replaced all previous printed guidance, including the booklet and aide memoire. These printed products are now out of date and should be securely destroyed.

NPSA has the right to remove access if the app is misused. Misuse includes sharing content outside approved audiences, reproducing content, retaining the app after it is no longer needed, or using it for purposes outside your role.

The app is available to authorised users at no direct cost, but access is restricted to those with approved work email domains. It is not available to the general public.

The app is classified at OFFICIAL. It contains information that should only be accessed by those who require it for their role.

Freedom of Information

This document is supplied in confidence and is exempt from disclosure under the Freedom of Information Act. It may also be subject to exemption under the Environmental Information Regulations and the Data Protection Act 1998. It must not be disclosed without prior reference to NPSA.

Disclaimer

This document has been prepared by the National Protective Security Authority (NPSA) and is provided for information purposes only. Whilst NPSA has taken reasonable care in producing it, no warranty is given as to accuracy or completeness. NPSA accepts no liability for any loss, damage, or proceedings arising from reliance on this document. Users should exercise their own judgement and seek independent professional advice as appropriate.

© Crown Copyright 2024

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