---
title: "ISO 7243 Measurement Standard | Aethair"
description: "ISO 7243:2017, Ergonomics of the thermal environment — Assessment of heat stress using the WBGT (wet bulb globe temperature) index, is the screening…"
url: https://aethair.io/standards/iso_7243/
---

Measurement method · ISO

# ISO 7243: heat stress assessment with the WBGT index

**ISO 7243:2017**, Ergonomics of the thermal environment — Assessment of heat stress using the WBGT (wet bulb globe temperature) index, is the screening method for heat stress. It defines how WBGT is measured from natural wet-bulb, globe, and air temperature, and how readings taken at different heights are weighted, so that the result can be compared with reference values for the work being done.

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At a glance

**ISO** Measurement method

1 parameter

[WBGT (Heat Stress)](https://aethair.io/parameters/wbgt/)

[Official text from ISO](https://www.iso.org/standard/67188.html)

Who uses it

## Who Uses It

Occupational hygienists, employers, and instrument makers assessing heat stress in hot workplaces, sport, and military training. The [ACGIH Heat-Stress TLV](https://aethair.io/standards/acgih_wbgt/) is expressed in the same WBGT.

Monitoring

## How It Relates to Monitoring

A WBGT instrument built to ISO 7243 measures the three temperatures directly (a natural wet bulb and a black globe, not an estimate from weather data) and can weight readings taken at ankle, abdomen, and head height. Continuous WBGT logging shows when the index approaches the limit for the current workload.

Devices

## Instruments Built to ISO 7243

Instruments in the sensor catalog that follow this method. Each connects to Environet through a Thiamis gateway.

Instruments built to it

[**TSI QUESTemp** Heat Stress & Comfort](https://aethair.io/sensors/tsi-heat-stress-comfort/)

Solutions

## Solutions That Rely on ISO 7243

### [Heat Stress & Outdoor Work](https://aethair.io/solutions/heat-stress/)

WBGT for worksites, athletics, and events

### [Weather Stations & Meteorology](https://aethair.io/solutions/weather/)

Professional multi-parameter weather monitoring

[All solutions](https://aethair.io/solutions/)

Questions

## ISO 7243 FAQ

What does ISO 7243 specify?

How to measure the WBGT index from natural wet-bulb, globe, and air temperature, and how to use it to screen for heat stress.

Can WBGT be estimated from weather data under ISO 7243?

No. The standard measures natural wet-bulb and globe temperature directly with the instrument.

How does ISO 7243 relate to the ACGIH heat-stress TLV?

The ACGIH Heat-Stress TLV is expressed in WBGT, the index ISO 7243 defines how to measure.