Combustible dust looks harmless. In the right conditions it can drive fires, flash fires, or explosions that stop production and put people at risk. OSHA continues to prioritize inspections for combustible dust hazards through its National Emphasis Program, which directs inspectors to evaluate dust deflagration risk factors across facilities. (OSHA)
If you lead safety, operations, or engineering, your challenge is practical. Identify where dust can form, collect or contain it, control ignition sources, and document compliance steps that stand up to audits. Hallam-ICS helps teams do this work with Dust Hazard Analyses, five-year updates, and mitigation design, but this guide stays focused on what you need to know today.
Combustible dust is finely divided solid material that can ignite or explode when dispersed in air and exposed to an ignition source. Many common materials become hazardous in dust form, which is why NFPA publishes combustible dust standards and OSHA enforces related hazards through the NEP. (awpa.org)
Common combustible dust examples include wood, grain and flour, sugar and starch, textile lint, coal or carbon black, aluminum and magnesium, plastic and rubber, pharmaceutical powders, and food powders like cocoa or spices. OSHA expects employers to assess these hazards, maintain housekeeping, train workers, and align with NFPA 660 requirements. (OSHA)
Use these examples to map your processes, then verify with a dust hazard analysis and material testing as needed. NFPA 660 requires an initial DHA and updates at least every 5 years.
Where it appears: Sawmills, furniture plants, pallet shops, MDF manufacturing.
Risk: Fine particulates can ignite from friction, hot surfaces, or electrical faults. Accumulations can fuel secondary explosions.
Where: Milling, baking, feed, and grain handling.
Risk: High surface area particulates. Conveying and milling create explosive dust clouds.
Where: Refineries, confectionery, and beverage plants.
Risk: Powdered sugar and starch are highly combustible. Layering on elevated surfaces increases severity.
Where: Spinning, weaving, and finishing lines; laundry and filter changeout.
Risk: Fibrous lint accumulates in concealed spaces and can flash when exposed to heat sources.
Where: Power, carbon black, pigment production.
Risk: Relatively low minimum ignition energy (MIE) and minimum explosible concentration (MEC) values make these dusts more prone to incidents.
Where: Finishing, grinding, polishing, machining, and additive manufacturing.
Risk: Metal fines are energetic. Incompatible collection methods can worsen hazards.
Where: Casting, machine shops, 3D printing powders.
Risk: Highly reactive. Water and some extinguishing agents can intensify events.
Where: Compounding, grinding, pelletizing, recycling.
Risk: Many polymers are combustible when finely divided. Static can be an ignition source.
Where: Blending, tableting, coating, and API handling in cGMP spaces.
Risk: Potent and combustible powders require contained transfer and engineered dust collection.
Where: Dry mixing, packaging lines, spray drying.
Risk: Highly combustible and easily dispersed during fill and transfer.
OSHA enforces combustible dust hazards through the National Emphasis Program (NEP) and existing standards. Practical focus areas:
1) Complete or update your DHA. NFPA 660 requires an initial DHA and periodic updates. The 2025 edition specifies five-year updates, and DHAs should also be revisited after significant process changes. (awpa.org)
2) Strengthen housekeeping. Define trigger levels for cleaning, include elevated surfaces, and verify methods do not create dust clouds. This is a frequent OSHA focus area under the NEP and 29 CFR 1910.22. (OSHA)
3) Engineer collection and ventilation. Correctly sized hoods, duct velocities, isolation valves, and explosion protection are essential. If you operate dust collectors, review performance and change controls routinely. For a practical dive, see Hallam-ICS guidance on why regular dust collector evaluations are mission-critical.
Internal link: why regular dust collector evaluations are mission-critical
4) Control ignition sources. Bonding and grounding, static control, hot work permits, intrinsically safe devices where required, and proper electrical area classification.
5) Build procedures and train. Train operators and maintenance on safe cleaning, start-up, shutdown, and upset conditions. Capture changes through MOC so new steps get reviewed in the DHA. (awpa.org)
6) Revisit at least every five years. Schedule your DHA update and verify that mitigation items are closed, documented, and auditable. (awpa.org)
|
Consideration |
Housekeeping focus |
Engineered collection focus |
|
Primary goal |
Remove settled dust before it becomes fuel |
Capture dust at the source to prevent accumulation |
|
Strengths |
Lower capital cost, improves inspection readiness |
Reduces airborne dust, supports continuous operations |
|
Gaps |
Labor intensive, may disturb dust |
Requires design, maintenance, and performance checks |
|
Best practice |
Define triggers, frequencies, and responsibilities |
Pair with isolation, explosion protection, and monitoring |
OSHA expects both a clean facility and evidence that systems are designed and maintained to minimize dust hazards. (OSHA)
What is combustible dust?
It is a finely divided solid material that can ignite or explode when dispersed in air and exposed to an ignition source. Many common industrial materials are combustible in dust form. (awpa.org)
Which NFPA standards apply to combustible dust?
As of 2025, NFPA 660 has consolidated and replaced NFPA 652 and the industry- or commodity-specific standards.
How often should a dust hazard analysis be updated?
Update at least every five years per the 2025 edition of NFPA 660, and after significant process changes. (awpa.org)
What does OSHA require for combustible dust?
OSHA enforces through the NEP and existing standards. Expect inspectors to look for a dust hazard analysis, housekeeping under 29 CFR 1910.22, training, ignition control, and alignment with NFPA 660. (OSHA)
What housekeeping basics reduce risk?
Keep surfaces clean, include elevated areas in your plan, and use cleaning methods that limit dust clouds. Define trigger levels, frequencies, and responsibilities in writing. (OSHA)
If you are evaluating ways to improve compliance and operational performance, our engineers are here to help. Let’s discuss how Hallam-ICS can support your next DHA, five-year update, and mitigation design so your people go home safe and your processes keep running.
About Hallam-ICS
Hallam-ICS is an engineering and automation company that designs MEP systems for facilities and plants, engineers control and automation solutions, and ensures safety and regulatory compliance through arc flash studies, commissioning, and validation. Our offices are located in Massachusetts, Connecticut, New York, Vermont, North Carolina and Texas, and our projects take us world-wide.