ISO 29042-9:2011

Overview

ISO 29042-9:2011, "Safety of machinery - Evaluation of the emission of airborne hazardous substances - Part 9: Decontamination index", defines a practical measurement method to quantify the decontamination index of pollutant control systems on machinery. The standard applies to capture devices (including local exhaust ventilation), water spray systems and separation equipment, using the real pollutant (per ISO 29042‑1) and can be applied in room or field environments. It is a Type‑B standard under ISO 12100 and is intended to help evaluate and compare the decontamination efficiency of control systems.

Key topics and requirements

• Three‑phase measurement:
  • Phase 1 - background concentration (machine and control system off).
  • Phase 2 - machine and pollutant control system operating (measure Cmi).
  • Phase 3 - machine operating with control system stopped or removed (measure Cai).
    Phases are repeated twice; sampling at each measurement point requires at least three readings.
• Decontamination index definition: the index I is the average, over specified measurement locations, of the ratio of ambient air quality improvement to the real pollutant mean concentration without control - effectively (C_a − C_m) ÷ (C_a − C_f). If background is negligible, I reduces to the average(C_a / C_m) − 1.
• Measurement point selection: pre‑testing to locate zones of measurable emission; type‑C standards may specify exact point numbers and positions.
• Data and instrumentation: record machine/process data, ventilation and room geometry, air flow rates, environmental conditions, and use calibrated instruments. Applicable flow and sampling standards (e.g., ISO 3966, ISO 5167‑1, ISO 5168) should be followed.
• Safety note: switching off pollutant control can raise hazardous concentrations; the standard warns of risks but does not prescribe protective measures.

Applications and users

ISO 29042‑9 is useful for:

• Manufacturers and designers of machines and pollutant control systems evaluating performance and demonstrating compliance.
• Test laboratories and occupational hygiene teams performing field or room tests of airborne hazardous substances.
• Safety engineers and ventilation specialists determining required air flow rate for a target decontamination level.
• Procurement and regulatory bodies comparing and ranking capture systems or assessing the state of the art.

Typical uses: performance evaluation, system improvement validation, comparative ranking, and establishing design targets for local exhaust ventilation and air cleaning.

Related standards

• ISO 29042 series (Parts 1–8) - selection of test methods, tracer and test bench methods, capture and separation efficiency, pollutant concentration parameters.
• Measurement and flow standards: ISO 3966, ISO 4006, ISO 5167‑1, ISO 5168, ISO 7708.

Keywords: ISO 29042-9, decontamination index, pollutant control system, capture device, local exhaust ventilation, airborne hazardous substances, emission evaluation, air flow rate, machinery safety.