PM10 Monitoring
PM Monitoring · PM Monitoring overview
PM10 is the mass concentration of airborne particles with an aerodynamic diameter of 10 µm or less. In UK workplaces, PM10 monitoring is used to characterise coarser particulate from mechanical processes, vehicle movement, material handling and infiltration of outdoor air, alongside occupational dust exposure assessment under COSHH.
What PM10 means
PM10 is defined by a size-selective sampling convention with a 50% cut at 10 µm aerodynamic diameter. It spans the thoracic size range and includes the smaller PM2.5 fraction within it. Particles in the PM10 range can reach the conducting airways, with the finer subset reaching the deep lung.
PM10 is reported as a mass concentration in micrograms per cubic metre (µg/m³). It originated as an ambient air quality metric and is widely used in workplace particulate mapping where coarse and mechanical-source particulate is the dominant contribution.
Why particle size matters
PM10 monitoring is most informative when reported alongside PM2.5. The ratio between the two indicates whether the airborne particulate is dominated by mechanical processes (which generally enrich PM10) or by combustion and fume sources (which generally enrich PM2.5). Splitting an aerosol into mass fractions gives a clearer picture of likely sources and deposition behaviour than a single total mass figure.
PM10 does not, in itself, identify any specific substance. It is a size-fraction mass measurement, useful for screening and source-tracking rather than as a substitute for substance-specific COSHH sampling.
Workplace sources of PM10
Typical workplace contributions to PM10 include:
- Mechanical dust generation: cutting, grinding, sanding, mixing and powder handling.
- Vehicle movement on indoor surfaces, including FLT traffic and yard infiltration.
- Re-suspension of accumulated settled dust by activity and air movement.
- Construction and refurbishment activity within or adjacent to the workplace.
- Bulk material transfer, tipping, screening and storage operations.
- Infiltration of outdoor coarse particulate through doors, vents and the building envelope.
PM10 monitoring versus occupational dust exposure assessment
PM10 monitoring and a COSHH dust exposure assessment are complementary rather than interchangeable. A COSHH assessment using HSE MDHS 14/4 and EH40 quantifies a specific substance against its Workplace Exposure Limit, typically as the inhalable or respirable fraction. PM10 quantifies total coarse-fraction mass without speciation.
PM10 results cannot be compared to substance-specific WELs and do not satisfy COSHH where a hazardous substance with its own WEL is present. PM10 is most useful for mapping particulate distribution across a site, identifying contributing tasks and zones, and providing the evidence base for where targeted COSHH sampling is needed.
How PM10 monitoring is selected
Workplace PM10 monitoring is most commonly performed with calibrated optical particle counters or light-scattering monitors logging at short intervals. Static instruments are deployed to map an environment over representative shifts; portable instruments can profile specific zones and tasks. Where defensible reference mass concentrations are required, real-time data is supported by parallel gravimetric sampling using a PM10 size-selective inlet onto a pre-weighed filter.
Sampling strategy is shaped by the question. Mapping work typically uses multiple loggers in fixed positions running continuously. Source-tracking work uses shorter, task-based deployments with event analysis. Continuous verification typically uses fixed installations with periodic gravimetric calibration and data review.
Interpreting PM10 results cautiously
PM10 concentrations vary strongly with activity patterns, housekeeping, ventilation, outdoor weather and material conditions. Short-duration measurements can be misleading, and apparent peaks should be tied back to specific events before drawing conclusions. Trends and event-based analysis are usually more useful than isolated values.
Optical instruments are sensitive to particle size, shape and refractive index. Different aerosols can produce different mass estimates at the same true concentration. Gravimetric calibration in the actual workplace aerosol is usually required where regulatory or contractual benchmarks apply.
Control considerations
Where PM10 mapping identifies elevated zones or recurring tasks, the COSHH hierarchy of control applies in the same way as for any airborne particulate. Reducing release at source — through enclosure, on-tool extraction, wetted methods, and improved housekeeping using HEPA-filtered vacuuming rather than dry sweeping or compressed air — is normally more effective than relying on dilution ventilation or PPE.
Where infiltration of outdoor PM10 contributes, improving intake filtration and door management may be relevant; for vehicle-driven re-entrainment, traffic management, surface cleaning regimes and load handling practices are typical levers.
When to review PM10
PM10 monitoring is a useful step where dusty processes are present, after process or layout changes, where occupants report visible dust or air quality concerns, when investigating soiling or housekeeping problems that suggest poorly controlled particulate, and as continuous verification in environments where coarse particulate must be managed.
Frequently asked questions
Is there a UK workplace WEL for PM10?
HSE EH40 does not set a substance-independent WEL for PM10. Workplace particulate is assessed against substance-specific WELs (typically as inhalable or respirable fractions). PM10 is used as a particulate mapping and screening metric, not as a regulated exposure limit.
Is PM10 the same as inhalable dust?
No. PM10 is a size-fraction mass with a 50% cut at 10 µm aerodynamic diameter, defined for ambient air quality monitoring. Inhalable dust is defined by a different size-selective convention (median around 100 µm) and is sampled using IOM-type heads under HSE MDHS 14/4 for COSHH purposes.
Can PM10 monitoring satisfy COSHH?
PM10 monitoring on its own does not satisfy COSHH where a specific hazardous substance with its own WEL is present. It can complement COSHH sampling by mapping particulate distribution and identifying where targeted substance-specific sampling is justified.
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