ISO 13732-3:2005

Overview

ISO 13732-3:2005 - Ergonomics of the thermal environment - Methods for the assessment of human responses to contact with surfaces - Part 3: Cold surfaces provides standardized methods and ergonomics data to assess risks when bare skin touches cold solid surfaces. The standard defines how to evaluate acute effects (pain, numbness, frostbite) and supports setting surface temperature limit values for products, machinery and workplaces. It applies to healthy adult skin and covers both finger touching and hand gripping contacts.

Key Topics

• Scope and purpose: Methods for assessing risk of cold injury and adverse effects from direct skin contact with cold surfaces; data intended for inclusion in product-specific (type C) standards.
• Contact classifications:
  • Finger touching: short contacts (up to 120 s) with a small contact area.
  • Hand gripping: longer contacts (up to 1 200 s) with sustained grip.
• Threshold concepts: Defines temperature/time relationships (threshold curves) for three main effects: pain (~15 °C contact temperature), numbness (~7 °C), and frostbite (contact temperatures at or below 0 °C) - expressed as material-specific curves.
• Material influences: Thermal properties of materials (aluminium, steel, stone, nylon, wood, etc.) strongly affect cooling. The standard uses thermal inertia and the thermal penetration coefficient (contact factor Fc) to relate material behaviour to skin cooling.
• Measurement requirements: Surface temperature should be measured under real operating conditions using thermocouples. Instrument accuracy: ±0.5 °C between −25 °C and +5 °C, and ±1 °C below −25 °C.
• Risk assessment process: Identification of touchable surfaces, task analysis (intentional/unintentional contact, frequency, duration, contact area/force), comparison with threshold data, and determination of required protective measures.
• Supporting annexes: scientific background, extension of application, thermal properties of selected materials, examples of risk assessment, and protective measures.

Applications and users

ISO 13732-3 is practical for:

• Product and machine designers setting safe surface temperatures
• Safety engineers and ergonomists conducting occupational risk assessments
• Standards developers and certification bodies defining temperature limits
• Health & safety officers, PPE designers, and maintenance teams evaluating cold-contact hazards Use cases include cold storage equipment, refrigerated machinery, metal tools, frozen-product handling, and any environment where ungloved skin may contact cold solids.

Related standards

• ISO 13732-1 (Hot surfaces)
• ISO/TS 13732-2 (Human contact with surfaces at moderate temperature)
• ISO 12100 (safety of machinery - basic concepts)
• ISO 7726 (measurement of physical quantities for thermal environment)

Keywords: ISO 13732-3:2005, ergonomics of the thermal environment, cold surfaces, surface temperature limits, contact period, frostbite, numbness, pain, risk assessment, threshold values.