CMR substances in the workplace: recirculated air, exhaust air, and W3—what applies?

What applies to CMR substances in the workplace?

CMR substances (also known as CMRs) are an issue in occupational health and safety where there can be no “gray areas.” This is because as soon as substances are classified as carcinogenic, mutagenic, or toxic to reproduction, the requirements for protective measures, documentation, and operation increase significantly.

This article serves as a guide for HSE officers, production managers, and technical purchasing.

1) CMR/CMR explained briefly: What does it stand for?

CMR stands for:

C: carcinogenic
M: mutagenic
R: toxic to reproduction (toxic to reproduction)

Important for your practice: It is not a question of “a lot or a little,” but rather a substance- and process-related assessment that you, as the operator, must document clearly.

2) Recirculated air or exhaust air? The basic logic behind KMR

As a general rule, if process emissions do not pose any particular hazards, recirculated air operation is often possible. However, in the case of CMR substances, guidelines and technical rules generally recommend or require the operator to use exhaust air.

In addition, the documentation explicitly states that extracted air containing CMR substances of categories 1A and 1B must not be allowed to enter the breathing air.

Practical conclusion: Two questions are central to your decision:

Are the emissions particulate or gaseous?
Has a sufficient separation efficiency been proven for recirculation mode?

3) Particulate CMR substances: Recirculation only with confirmed separation efficiency (e.g., W3)

The following applies to particulate CMR substances:

Recirculating air operation only with W3-approved system – otherwise exhaust air.

In addition, the following describes how verification is intended to work in practice:

In recirculating air operation, the separation efficiency during commissioning must be verified by the operator using a tested procedure.
If the verification is insufficient, the filtered air must be discharged to the outside.
Alternatively, a type-tested extraction and filter system with a confirmed separation efficiency (e.g., according to DIN EN 60335-2-69 Annex AA or W3) can be used.

4) Gaseous CMR substances: Exhaust air or sensor technology with alarm

The following applies to gaseous CMR substances:

Exhaust air ducting or monitoring of the filtered air with measuring sensors and signaling when limit values are exceeded.

If it is not possible to vent to the outside, the operator must monitorthe AGW at the outlet.

Important: Gaseous substances require different filter concepts than pure particles, including the adsorption of gaseous substances with activated carbon granulate and molecular sieves against gaseous pollutants.

5) What does W3 mean – and why is it relevant for CMR?

TBH systems are tested in accordance with DIN ISO 21904 (W3) and the IFA confirms the systems (including in the IFA positive list).

If you have CMR processes in operation, W3 (or a confirmed separation efficiency in accordance with the relevant standard) is relevant because it concerns verifiable protection during recirculation operation.

6) Checklist for HSE & production: How to structure your assessment

To help you reach a reliable decision more quickly internally, follow this sequence:

Identify substances & check classification (safety data sheet, internal hazardous substances list, CMR classification).
Clarify emission type: particulate or gaseous (or both).
Define the operating concept: Exhaust air vs. Recirculating air (if recirculating air: consider verification/standard requirements).
Prioritize capture at the point of origin (technical protective measures generally follow the logic: avoid → extraction → ventilation measures → PPE).
Plan verification & operating obligations (e.g., testing/maintenance logic, measurement concept) .
Update documentation (risk assessment, operating instructions, training).

7) How TBH supports – without unnecessary complexity

TBH describes that filter and extraction systems have a separation efficiency according to W3 confirmed by the IFA and can also be used for the extraction of CMR substances. In addition, equipment features are mentioned that are particularly relevant for sensitive processes (e.g., HEPA H13-H14 filters, signaling on the display, volume flow meter, signal module, interface with error evaluation, filter principles such as activated carbon adsorption and molecular sieve).

Note:

This article is a practice-oriented summary and does not replace a site-specific risk assessment. The specific design (recirculating air/exhaust air, measurement concept, filter configuration) always depends on the substance, process, and general conditions.

Would you like to classify your application (particulate/gaseous, recirculating air/exhaust air, detection requirements) in a structured manner?

Please send us the following information:

Substance/material + safety data sheet (if available)
Process description (source, cycle, enclosure)
Desired operating concept (recirculating air/exhaust air)
Target values/limit values or internal HSE specifications

More information: Contact – TBH GmbH Filter and extraction systems