Not all dust behaves the same. On site we deal with a mix of particle sizes and shapes that determine how far they travel into the body and how hard they are to remove from the air. Understanding inhalable versus respirable fractions is key to choosing the right extraction, filtration and housekeeping.

What counts as inhalable and respirable?

Inhalable dust consists of particles that can enter the nose and mouth; much of this is captured by the upper airway. Respirable dust is small enough to reach the gas-exchange region of the lungs. In practice we discuss PM10 (thoracic), PM2.5 and PM1, and occupational samplers often refer to a respirable cut around the PM4 range. RCS from concrete, stone and brick is predominantly respirable; hardwood dust is mostly inhalable and linked with nasal cancer.

Under HSE EH40, RCS has a WEL of 0.1 mg/m³ (8-hour TWA). Wood dust is 3 mg/m³ (hardwood, or mixed). COSHH requires assessment, control and maintenance of measures. OSHA limits are similar in intent, but UK sites should follow HSE first.

Controls matched to particle size

1) Capture at source (prevention)

For inhalable dust from cutting and sanding, tool-mounted extraction with appropriate shrouds and water suppression cuts release. Slower feed rates reduce particle generation. Design out dry cutting where possible.

2) Capture in the air (control)

Air scrubbers, LEV and negative air machines reduce airborne load. Specify multi-stage filtration with a final HEPA stage; for respirable and carcinogenic hazards such as RCS, select H14 at the final stage. Size systems by the real duty point and confirm airflow under load.

3) Capture on surfaces (housekeeping)

Prevent resuspension. Avoid sweeping and compressed air. Use industrial vacuums (commonly M-Class or H-Class) with high-efficiency filters and tight seals. Service schedules should reflect filter loading and duty cycles.

Measuring what matters

Use a particulate monitor or laser particle counter to spot trends and confirm improvements after introducing controls. Personal sampling may still be needed for compliance decisions, but area monitoring is invaluable for daily management, changeovers and maintenance planning.

Practical takeaways

• Identify whether your task generates inhalable or respirable dust.
• Match filtration: H14 final stage for respirable/carcinogenic hazards.
• Check airflow under load; do not rely on free-air figures.
• Ban sweeping; use serviced industrial vacuums for housekeeping.
• Monitor PM levels to verify controls and trigger filter changes.

Choosing controls that align to particle behaviour improves protection and reduces rework. Treat monitoring and maintenance as part of the control, not an afterthought.