NFPA 660 Arrives: Combustible Dust Rules Cannabis and Hemp Processors Must Implement Before 2026

The arrival of NFPA 660: Standard for Combustible Dusts and Particulate Solids is reshaping how U.S. cannabis and hemp processors protect their facilities, staff, and products. As regulatory enforcement shifts sharply toward this unified standard in 2025, processors face new challenges—and opportunities—for improving compliance and safety.

Gain clarity on what NFPA 660 means for your operations, what fire marshals and insurers now expect, and how to build NFPA 660 cannabis compliance into daily SOPs before permit renewals and underwriting in 2026.

What is NFPA 660? A New Chapter for Cannabis Safety

Adopted at the end of 2024 and already referenced across Authorities Having Jurisdiction (AHJs) in 2025, NFPA 660 consolidates combustible dust guidance from legacy standards—including NFPA 652 (Fundamentals), 654 (General Industry), and 61 (Agricultural—directly relating to hemp and cannabis biomass processing). With dust explosion incidents causing millions in damages and facility shutdowns annually, regulators and insurance underwriters now look to NFPA 660 as the baseline for risk management.

Key cannabis and hemp dust hazard scenarios:

• Grinding and milling dried biomass (trichome-rich dust is highly combustible)
• Tablet pressing for edibles (fines accumulate in equipment and vents)
• Sugar, starch, and confectionery operations (fine organic dusts)
• Packaging areas (dust from pre-rolls, dried flower, hemp)
• Drying and decarboxylation lines with ignition potential

NFPA 660 aims to close gaps in prior standards—requiring comprehensive documentation, dust hazard analysis, and specific engineering controls.

Dust Hazard Analysis (DHA): Maintained and Strengthened

NFPA 660 maintains the Dust Hazard Analysis (DHA) mandate, requiring every processor to systematically identify, evaluate, and mitigate combustible dust hazards at every stage of the workflow.

DHA Requirements for Cannabis/Hemp Facilities:

• Map out all areas where dust is generated or may accumulate—including ancillary spaces like utility chases, drop ceilings, and conveyor enclosures.
• Identify ignition sources (e.g., electrical panels, friction from moving parts, static) close to dust-producing operations.
• Rank and document each scenario for likelihood and consequence of fire/explosion.
• Revalidate the DHA at least every 5 years—or when processes, vendors, or layouts change.

Best Practice: Engage process safety and industrial hygiene experts who understand cannabis-specific risks to ensure the DHA passes both insurer reviews and fire safety inspections.

For a deeper dive, see: Dust Hazard Analysis: Preparing for NFPA 660 Compliance (ei1.com).

Engineering Controls: Dust Collection and Explosion Protection

Modern Dust Collection

Processors must confirm that dust collection systems—baghouses, cartridge collectors, or ambient collectors—are properly rated for the Kst (explosibility index) and PMAX (maximum explosion pressure) relevant to cannabis biomass dust. Systems must not only capture dust at its source, but also minimize secondary accumulation on floors, overheads, and inside equipment.

NFPA 660-compliant systems must:

• Employ listed explosion vent panels, suppression devices, or isolation valves where required.
• Be sized and maintained to avoid overloading (frequent cleaning, no overloaded filters).
• Feature interlocks that shut down upstream grinders, fans, or conveyors if a collector fault or explosion risk is detected.
• Include bonded and grounded ductwork to dissipate static charges.

Tip: Document PMAX/Kst ratings from your collector vendor, and ensure certificates are included in compliance files for AHJ and insurance audits.

Learn more: ACT Dust Collectors: NFPA 660 Compliance Guide

Zoning and Segregation

• Milling and grinding rooms should be physically segregated from other plant operations, using fire-resistant barriers and separate air handling.
• Confectionery or edible production zones require dedicated dust collection for sugar/starch containment.
• Utility/electrical rooms should be separated from dust-generating processes to limit ignition risk.

Housekeeping & Preventative Maintenance

NFPA 660 sharpens requirements for documented housekeeping to prevent hazardous dust accumulations.

Best Practices Include:

• Implement a cleaning program with defined frequencies (daily, weekly, post-shift)—inspect not just visible surfaces but also elevated/hidden areas.
• Ban dry sweeping; use only HEPA-rated industrial vacuums and wet methods where safe.
• Keep detailed maintenance logs for dust collectors, noting filter changes, differential pressure checks, and emergency repairs.
• Regularly inspect and clean equipment, light fixtures, ducts, and plenums where fines may collect unnoticed.

For more tips: Goodway: Essential Dust Collection Tips (goodway.com)

Ignition Source Control & Process Interlocks

Decarboxylation, drying, and any heated process lines are flashpoint risks. NFPA 660 expects:

• Proximity sensors and automatic shutoffs for grinders, dryers, or conveyors if abnormal dust levels are detected.
• Grounding straps and bonding for all metallic process and transfer equipment.
• Over-temperature/interlock sensors tied to facility alarms.

All modifications—new equipment, re-routing of ducting, or process changes—must be documented as part of a Management of Change (MOC) process, flagged for DHA review and regulatory inspection.

Insurance and Fire Marshal Trends for 2025

As underwriting and fire inspection cycles shift to NFPA 660, expect:

• Inspectors to demand written proof of current DHA covering all cannabis-relevant hazards.
• Requests for dust collector performance documentation (Kst, PMAX, cleaning records).
• Verification that SOPs and staff training include NFPA 660 references and site-specific responsibilities.
• Permits and insurance policies may be denied or delayed if legacy NFPA 652/654 documentation is not updated to the 660 format.

Tip: Proactively invite your AHJ or insurer to review control measures before critical renewal dates.

Cannabis-Specific NFPA 660 Checklist for 2025 Compliance

Strategic Steps Before Your Next Renewal or Inspection:

• [ ] Commission or update a formal Dust Hazard Analysis covering all biomass/process points
• [ ] Obtain vendor certifications for Kst/PMAX, collector ratings, interlock functionality
• [ ] Physically segregate grinding/milling, packaging, and edible confection zones
• [ ] Institute written housekeeping and preventive maintenance schedules/logs
• [ ] Ban dry sweeping; inventory and deploy only NFPA-compliant cleaning tools
• [ ] Ground and bond all dust-conveying equipment (verify with a certified electrician)
• [ ] Document and manage all process changes and equipment upgrades in an MOC log
• [ ] Train all staff on new SOPs, post quick-reference signs in high-risk areas
• [ ] Schedule an internal or third-party NFPA 660 compliance audit annually

Conclusion: Start Now for NFPA 660 Cannabis Compliance

2025 is a year of transition as NFPA 660 becomes the new language of combustible dust risk management. Cannabis and hemp businesses that treat this as an opportunity—investing in updated analyses, engineering controls, and documentation—will not only satisfy AHJs and insurers, but foster a safer, more sustainable workplace as regulations mature.

Don’t wait for renewal deadlines or enforcement visits: Be proactive, benchmark against the new NFPA 660, and empower your teams for a compliance-driven culture.

For the latest regulatory intelligence, tools, and more cannabis compliance guidance, visit CannabisRegulations.ai and get ahead of tomorrow’s standards.