Check that the category fits
The INSST occupational exposure limits database restricts this reference to particles without a specific limit that are insoluble or poorly soluble and have low toxicity. It excludes effects such as genotoxicity, sensitisation or harm other than pulmonary accumulation.
It also states that the particulate matter must not contain asbestos or crystalline silica. The traditional term “nuisance dust” does not demonstrate that these conditions are met.
Identify before comparing
The review must consider raw materials, additives, coatings and contaminants generated by the process. An apparently simple product may produce a particle mixture containing components requiring their own assessment.
If composition is unknown, further information or characterisation is needed. Measuring dust mass and comparing it directly with the generic value may conceal significant exposure to a specific substance.
Distinguish inhalable and respirable fractions
NTP 731 explains sampling conventions by particle size. Inhalable and respirable fractions represent different parts of the aerosol and require appropriate devices and criteria.
They are not synonyms for visually estimated “large dust” and “small dust”. The report must identify the measured fraction and compare it with the corresponding reference, without interchanging results.
Represent actual tasks
Royal Decree 374/2001 requires exposure conditions to be considered. The strategy must cover emitting tasks, process variations and groups of workers with comparable exposure.
Sampling far from the person or during a low-emission phase may not represent their shift. Record the activity, duration, equipment operating and circumstances influencing the result.
Control generation and dispersion
Prevention must act at source through supply forms, enclosures, extraction and handling methods that reduce emissions. Cleaning must prevent deposited material from becoming airborne again.
The absence of identified specific toxicity does not remove the need for control. Respiratory protection is selected according to the assessment and complements technical measures where necessary.
Review conclusions when the material changes
A change of supplier, composition or process may invalidate use of the generic category. The assessment must retain the justification for its selection and review it when new toxicological information or relevant results become available.
Numerical comparison also does not resolve other dust risks, such as fire or explosion where relevant. Occupational hygiene and safety assessments have different objectives and must be coordinated.
Hypothetical example: sanding a component
A workshop has a respirable dust measurement but changes the material used in its components. Before reusing the previous conclusion, it reviews composition and coating.
If a component with its own limit or hazards is identified, it adapts the analysis. The generic value is no longer used as a substitute for missing information.
