This document specifies sampling conventions for airborne particle size fractions to assess health-related exposure resulting from the inhalation of particles in workplace atmospheres. Conventions are defined for the inhalable, thoracic and respirable fractions. The sampling conventions only describe the inhalation of particles and their penetration in the respiratory tract as governed by inertia (impaction). Exhaled particles and deposition in the respiratory tract by other mechanisms, e.g. diffusion, are not considered in this document. The sampling conventions defined in this document apply to both indoor and outdoor workplaces. The conventions assume particles penetration and only oral breathing as a worst-case scenario. Nevertheless, the conventions are applicable to both oral and nasal breathing.
The conventions are defined based on assumptions given in Clause 6. The choice of convention for a specific application depends on the region of the respiratory tract affected by the health impact of the particle component of interest (see Clause 5). The conventions can be applied to various metrics, including particle number, length, surface area, volume, or mass, depending on the type of particle analysis performed on the sampled aerosol fraction. The health-related fraction concentrations defined in this document are often expressed as the mass of sampled particles per volume of sampled air to allow comparison with mass-based occupational exposure limit values.
The conventions primarily apply to the aforementioned metrics, however, they are not applicable to situations involving limit values expressed in a different metric, such as fibre limit values defined by length, diameter, and aspect ratio, unless a measurement procedure explicitly specifies sampling a particular health-related size fraction [11].
The primary objective of this document is to establish standardized conventions for health-related particle size fractions. Sampling is generally carried out using dedicated samplers, for which there is no need to measure the aerodynamic size distribution of the airborne particles to be sampled. Samplers separating airborne particles into one or more relevant fractions are currently available. In general, no assumptions or pre-knowledge are needed on the number of modes, modal diameter(s) or width of the particle aerodynamic size distribution of the airborne particles to be sampled.
The conventions in this document are intended to be used for the determination of the exposure of an average worker based on average penetration curves. This document is not intended to determine the deposited dose of an individual worker.
The conventions are primarily intended for assessing workers’ exposure to airborne particles by sampling the airborne particles. This document does not apply to large particles emitted at high speed that travel due to their initial momentum, instead of being carried by the air (airborne) and aspirated into humans’ respiratory tract and aerosol samplers by suction (see Annex B).
All wind speeds referenced throughout this document are based on the relative speed between the worker and the surrounding air.
