Making Sense of Combustible Dust DHAs vs. a PHA

Process Hazard Analyses (PHAs) have been conducted for decades across the chemical processing industries. First conceived at ICI in the 1960s, the PHA process has been continually refined to identify, understand, and mitigate risk. Today, hazard analysis has now solidified its place in combustible dust hazard management. When applied specifically to combustible dust handling environments, this systematic review is known as a Dust Hazard Analysis (DHA).

For all industrial operations, the fundamental premise of any hazard evaluation remains identical: identifying hazards, understanding causes/consequences, identifying adequate safeguards and assessing the risks associated with each hazard.

However, a critical question arises for safety professionals, particularly those in the chemical industry sectors: How is a traditional PHA truly different from particulate solids or dust-focused DHA?

In dust-handling facilities, the primary hazard—combustible particulate solids—is already well-known. Hidden, complex chemical reaction hazards rarely surface during a particulate solids’ evaluation. Instead, the challenge lies in managing a solid material that naturally migrates, settles, and disperses.

The regulatory landscape reached a historic milestone with the publication of NFPA 660 (2025), the unified Standard for Combustible Dusts and Particulate Solids. NFPA 660 consolidates all legacy industry-specific standards into a single, comprehensive framework and defines DHA as:

"A systematic review to identify and evaluate the potential fire, flash fire, or explosion hazards associated with the presence of one or more combustible particulate solids in a process or facility." (NFPA 660, 2025)

This paper will outline the most current dust hazard analysis requirements, to best complete those requirements to meet regulations, as well as internal obligations to maintain a safe work environment.