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ISO 29042-1:2008 — Safety of Machinery — Evaluation of Emission of Airborne Hazardous Substances — Part 1: Selection of Test Methods
A comprehensive guide to selecting test methods for evaluating emission of airborne hazardous substances from machinery according to ISO 29042-1
Introduction to ISO 29042-1
ISO 29042-1:2008 is a Type-B safety standard that provides the framework for evaluating the emission of airborne hazardous substances from machinery. It specifies parameters that can be used for assessing pollutant emissions from machines or the performance of pollutant control systems integrated in machines. As the foundational document of the ISO 29042 series, this standard guides users in selecting the appropriate test methods from subsequent parts (Parts 2-9) based on their specific application requirements and machine types.
For machinery safety engineers, ISO 29042-1 is essential reading before proceeding to any of the specific test method parts. It provides the decision framework for matching test methods to machine types, helping avoid costly and inappropriate testing. Selecting the wrong test method can lead to non-representative emission data and inadequate risk assessment.
The standard addresses two fundamental parameters: the emission rate of pollutants from the machine itself, and the performance of pollutant control systems (such as exhaust ventilation, filtration, and containment). It distinguishes between uncontrolled emission rate (without pollution control measures active) and controlled emission rate (with control measures active), enabling assessment of both the machine inherent emission and the effectiveness of control systems.
Key Parameters and Test Method Selection
Emission Parameters Defined
ISO 29042-1 defines several key parameters for characterizing machine pollutant emissions. The uncontrolled emission rate represents the mass of pollutant emitted per unit time when no control measures are activated. The controlled emission rate represents the mass emitted when control measures are active. The capture efficiency of exhaust systems and the separation efficiency of air cleaning systems are also defined as critical performance parameters.
| Parameter | Symbol | Definition | Application |
|---|---|---|---|
| Uncontrolled emission rate | mu | Mass of pollutant per unit time without controls | Machine inherent pollution potential |
| Controlled emission rate | mk | Mass emitted with pollution control measures active | Real-world machine performance |
| Capture efficiency | eta-c | Fraction of pollutant captured by exhaust system | LEV performance assessment |
| Separation efficiency | eta-s | Fraction removed by air cleaning system | Filter/separator performance |
| Pollutant concentration | C | Mass concentration in workplace air | Worker exposure assessment |
A critical point for test selection is recognizing that not all test methods apply to all machine types. For example, the tracer gas method (Part 2) is suitable only for gaseous pollutants, while test bench methods (Parts 3, 5, 6) are designed for particulate pollutants. Applying the wrong method can produce meaningless results and a false sense of safety.
Decision Framework for Test Selection
The standard provides a structured decision framework based on the type of pollutant (gas, vapour, aerosol, dust), the machine configuration (with or without integrated exhaust), and the intended use of the test data (type testing, commissioning, or in-service monitoring). A key decision point is whether the machine has an integrated pollutant control system. If yes, the capture efficiency and separation efficiency become the primary parameters of interest. If no, the uncontrolled emission rate is the primary parameter.
Engineering Insights for Machinery Emission Control
ISO 29042-1 emphasizes that emission evaluation is only one component of a comprehensive risk assessment. The standard ISO 12100 provides the overall risk assessment framework, while ISO 14123-2 gives guidance on verification procedures for machines handling hazardous substances. The emission parameters defined in ISO 29042-1 feed into the risk assessment process by providing quantitative data on the potential for worker exposure.
For engineers designing machinery that processes hazardous substances, the standard implies several design principles. First, emission reduction should be prioritized at the source through process modification (enclosure, wetting, reduced temperature) before relying on exhaust systems. Second, the performance of control systems should be verifiable using the standardized test methods. Third, the emission data generated using ISO 29042 methods allows comparison between different machine designs and informs the selection of appropriate personal protective equipment.
Experience in industrial hygiene engineering has shown that the most cost-effective approach to reducing airborne hazardous substance emissions is source modification rather than end-of-pipe control. ISO 29042-1 supports this hierarchy by separately quantifying uncontrolled and controlled emission rates, allowing engineers to demonstrate the effectiveness of source reduction measures in directly comparable terms.
Frequently Asked Questions
Q1: How does ISO 29042-1 relate to occupational exposure limits (OELs)?
ISO 29042-1 does not define acceptable exposure levels. Instead, the standard provides methods for quantifying emission rates that can be used in combination with exposure models and OELs to assess whether a machine is likely to create hazardous workplace conditions under specified usage patterns.
ISO 29042-1 does not define acceptable exposure levels. Instead, the standard provides methods for quantifying emission rates that can be used in combination with exposure models and OELs to assess whether a machine is likely to create hazardous workplace conditions under specified usage patterns.
Q2: Can ISO 29042 be applied to all types of machinery?
The standard is applicable to machinery that processes or generates hazardous substances in airborne form. It is not applicable to machines that handle only non-hazardous materials or to situations where the primary risk is from direct contact rather than inhalation. The standard specifically excludes radioactive substances and biological agents.
The standard is applicable to machinery that processes or generates hazardous substances in airborne form. It is not applicable to machines that handle only non-hazardous materials or to situations where the primary risk is from direct contact rather than inhalation. The standard specifically excludes radioactive substances and biological agents.
Q3: What is the relationship between ISO 29042 and the EU ATEX directives?
ISO 29042 focuses on health hazards from airborne substances, while ATEX directives address explosive atmospheres. However, many combustible dusts present both health and explosion hazards. The emission quantification methods in ISO 29042 can provide inputs to dust explosion risk assessments when used with ISO 19353 and EN 1127-1.
ISO 29042 focuses on health hazards from airborne substances, while ATEX directives address explosive atmospheres. However, many combustible dusts present both health and explosion hazards. The emission quantification methods in ISO 29042 can provide inputs to dust explosion risk assessments when used with ISO 19353 and EN 1127-1.
Q4: How often should emission testing be repeated?
The standard distinguishes between type testing (performed once for a machine design) and in-service verification (performed periodically). Type testing is typically required for new machine designs or when significant modifications are made. In-service testing frequency depends on hazard severity and control system stability.
The standard distinguishes between type testing (performed once for a machine design) and in-service verification (performed periodically). Type testing is typically required for new machine designs or when significant modifications are made. In-service testing frequency depends on hazard severity and control system stability.
When implementing the ISO 29042-1 framework, engineers should develop a test plan that clearly identifies the target pollutants, the relevant emission scenarios (normal operation, start-up, shutdown, and foreseeable malfunction), and the appropriate test methods from Parts 2-9. The test plan should also specify the acceptance criteria for emission performance, which may be derived from occupational exposure limits, regulatory requirements, or company-specific health and safety policies. Documentation of the test plan and results forms an essential part of the machine technical file for CE marking compliance under the EU Machinery Directive.
A critical aspect of implementing ISO 29042-1 is the selection of appropriate performance metrics for the emission test. The standard framework supports both concentration-based and emission-rate-based metrics, each suited to different regulatory contexts and risk assessment approaches. Concentration-based limits are typically specified for workplace air quality compliance, while emission rate metrics are more appropriate for comparing the performance of different machines or evaluating the effectiveness of emission control technologies. Engineers should ensure that the chosen metrics align with the applicable regulatory framework and that the measurement uncertainty is accounted for in the conformity assessment process.
