ISO 16976-3:2022

Overview

ISO 16976-3:2022 - Respiratory protective devices - Human factors - Part 3 provides a human‑physiology foundation for assessing how variations in oxygen (O2) and carbon dioxide (CO2) in the breathing environment affect RPD (respiratory protective devices) users. The standard describes atmospheric gas composition, respiratory physiology and gas transport, and surveys biomedical literature on the effects of hypoxia, hyperoxia and hypercarbia. It identifies concentration/partial‑pressure limit values and exposure timeframes that are not expected to cause physiological distress, and addresses both low partial‑pressure scenarios (high altitude, aviation) and high partial‑pressure scenarios (underwater diving, hyperbaric conditions).

Key topics and requirements

• Human respiratory physiology: alveolar gas exchange, oxygen/carbon dioxide transport in blood, control of respiration.
• Physiological responses: effects and symptoms of hypoxia (low O2), hyperoxia (elevated O2), and hypercarbia/hypercapnia (elevated CO2).
• Partial pressure concepts: dependence of gas diffusion on partial pressure vs. volume fraction - critical for altitude and diving contexts.
• RPD relevance: guidance on how altered breathing gas environments can arise from filtering respirators (APR/PAPR), supplied air respirators (SAR/SCBA/UBA), escape devices (SCSR), or device malfunctions (e.g., CO2 buildup).
• Limit values and exposure durations: identification of concentration/partial‑pressure thresholds and associated time limits (standard describes these values; specific numeric limits are provided in the document itself).
• Interpretation and significance: how to interpret physiological test results and their implications for safe RPD use across different work rates.

Applications

• RPD design and development: inform breathing‑space design, CO2 scrubbing, and breathable gas selection.
• Selection and certification: supports occupational health and certification bodies in evaluating device safety under varied environmental pressures.
• Risk assessment and emergency planning: guidance for industries with altitude exposure (aviation, mountaineering), diving (commercial, military, recreational), confined spaces, and emergency escape systems.
• Occupational health & safety programs: set safe exposure limits, monitor wearer physiology, and define acceptable work rates when using RPD.

Who should use this standard

• RPD manufacturers and designers
• Occupational safety professionals and HSE managers
• Diving operations and hyperbaric medicine specialists
• Test laboratories and conformity assessment bodies
• Regulators, standards committees, and researchers in respiratory protection and human factors

Related standards

• Part of the ISO 16976 series on RPD human factors; use in conjunction with other ISO RPD standards and relevant occupational PPE guidance for complete compliance and product development.