ISO 7243-2017 PDF

Full title and description

ISO 7243:2017 — Ergonomics of the thermal environment — Assessment of heat stress using the WBGT (wet bulb globe temperature) index. This International Standard provides a screening method for evaluating heat stress exposure over a working day (up to 8 hours) using the WBGT index.

Abstract

Provides a simple, field-applicable screening method (the WBGT index) to estimate heat stress and to establish the presence or absence of heat stress for adults fit for work. The standard covers assessment methods for indoor and outdoor occupational environments, describes measurement and calculation of WBGT (including handling of solar radiation), and identifies limitations (not intended for very short exposures).

General information

• Status: Published.
• Publication date: 16 August 2017.
• Publisher: International Organization for Standardization (ISO).
• ICS / categories: 13.180 (Ergonomics).
• Edition / version: Edition 3 (2017).
• Number of pages: 18.

Key bibliographic and lifecycle details as published by ISO.

Scope

Applies to evaluation of the mean effect of heat on a person during a representative working period (up to 8 h). It is intended as a screening tool for indoor and outdoor environments, for male and female adults who are fit for work, and is not intended for very short exposures or detailed individual physiological assessment. The method supports occupational assessment and control decisions but does not replace detailed physiological or clinical evaluation.

Key topics and requirements

• Definition and use of the WBGT index as the screening metric for heat stress (combines natural wet-bulb, globe, and air temperatures depending on solar load).
• Measurement procedures and recommended instrument characteristics for natural wet-bulb and black-globe sensors, and guidance on instrument placement and corrections for solar radiation and wind.
• Formulas for WBGT calculation (indoor/outdoor variants) and procedures for estimating natural wet-bulb temperature when direct measurement is not possible.
• Clothing and work-rate adjustments: guidance on applying clothing corrections and considering metabolic rate when interpreting WBGT results.
• Use limits and cautions: screening nature of the method, not suitable for very short exposures or for predicting individual physiological response; recommends further assessment where WBGT indicates risk.

Technical measurement details and example formulas are provided in the standard and in implementation summaries that describe instrument specs and WBGT calculation variants.

Typical use and users

Used by occupational hygienists, safety and health professionals, ergonomists, facility and operations managers, event/sports safety planners, military health officers, and researchers to screen work/rest regimens, to set administrative controls (work/rest schedules, hydration, PPE/clothing guidance), and to trigger more detailed assessments or interventions when WBGT indicates elevated heat stress risk.

Related standards

Commonly used alongside other ergonomics/thermal-environment standards such as ISO 7933 (predicted heat strain / analytical methods), ISO 9886 (physiological measurements for thermal strain), ISO 8996 (determination of metabolic rate), and ISO 7726 (instrumentation for measuring thermal environment parameters). These documents provide complementary methods for prediction, physiological monitoring and instrument requirements.

Keywords

WBGT; wet-bulb globe temperature; heat stress; ergonomics; thermal environment; occupational hygiene; heat strain; screening method; heat assessment; black globe; natural wet-bulb.

FAQ

Q: What is this standard?

A: ISO 7243:2017 is an International Standard that specifies a screening method to assess heat stress using the WBGT index for adult workers over a typical working day.

Q: What does it cover?

A: Measurement and calculation of the WBGT index (including guidance for natural wet-bulb and globe temperature measurements), application limits, clothing and work-rate adjustments, and use as a screening tool to identify heat-stress risk in occupational and similar environments.

Q: Who typically uses it?

A: Occupational hygienists, safety and health professionals, ergonomists, facility managers, sports and event safety planners, military health personnel, and researchers performing heat-stress screening and setting control measures.

Q: Is it current or superseded?

A: The 2017 edition (Edition 3) is the current published version that replaced earlier editions (e.g., the 1989 version). Consult ISO or national adopters for the latest review status.

Q: Is it part of a series?

A: It is part of the ISO/TC 159 ergonomics of the thermal environment family of standards and is commonly used with ISO 7933, ISO 9886, ISO 8996 and ISO 7726 for comprehensive assessment and instrumentation guidance.

Q: What are the key keywords?

A: WBGT, wet-bulb globe temperature, heat stress, ergonomics, thermal environment, occupational hygiene, heat strain.