ISO 22324:2022

Overview

ISO 22324:2022 - "Security and resilience - Emergency management - Guidelines for colour‑coded alert" provides international guidance on using colour-coded alerts to inform people at risk and first responders about hazard severity. Applicable to all hazards and locations, the standard clarifies colour meanings, ordering, supplementary codes and human-factor considerations to reduce confusion and prompt appropriate safety actions.

Key topics and technical requirements

• Primary colour meanings
  • Red = danger - take safety action immediately
  • Yellow = caution - prepare to take safety action
  • Green = safe - no action required
• Supplementary colours
  • Black / Purple = fatal danger (may be combined with red; checkerboard recommended on luminous displays)
  • Blue = informational only (do not use to indicate hazard level)
  • Grey = no information available
• Spectrum and ordering
  • Use the red–yellow–green spectrum; if ordered visually, present increasing hazard left→right or bottom→top.
  • Limit the number of levels (prefer minimal levels); use no more than seven colours to avoid confusion.
• Supplemental cues
  • Always add supporting information (text, numbers, symbols, position or size) especially when more than three levels are used or when colour discrimination is limited.
• Human factors & accessibility
  • Account for colour-blindness and viewing conditions; do not rely on colour alone for safety-critical decisions.
  • Recommended text contrast for superimposed labels: white over black/purple/red/green; black over yellow.
• Colour specifications
  • Annex B gives recommended hues in Munsell, CMYK and RGB systems for consistent implementation.
• Scope exclusions
  • The standard does not cover display methods, detailed ergonomics of viewing displays, or safety sign formats covered by ISO 3864‑1.

Practical applications

ISO 22324 is designed for practical use in:

• Public warning systems and emergency management operations
• Early-warning dashboards, control rooms and digital alert displays
• Incident triage systems, maps (meteorological, radiological), and mass notification messages
• Emergency planning, training and communication templates

Benefits include clearer public warnings, reduced misinterpretation of alert levels, and improved cross‑agency consistency in colour-coded messaging.

Who should use this standard

• Emergency managers, public safety officials and civil protection agencies
• UX/UI designers for control-room and public-alert interfaces
• Authorities responsible for public warning, disaster communication and signage
• Vendors of alerting systems and digital signage

Related standards

• ISO 22322 - Public warning guidance
• ISO 22300 - Vocabulary (security and resilience)
• ISO 3864‑1 - Safety colours and safety signs (scope exclusion)
• ISO/TR 22411 and ISO 9241‑300 - Ergonomics and colour considerations
• ISO/IEC Guide 71 - Accessibility considerations for colour blindness

Keywords: ISO 22324, colour-coded alert, emergency management, public warning, hazard colour codes, red yellow green, accessibility, alert design.