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Dry Particulate

Last updated: May 16, 2019

What Does Dry Particulate Mean?

Dry particulate matter refers to hazardous solid particles that are small enough to enter the human body (particularly the lungs), potentially resulting in health problems.

Particulate matter (PM) can consist of solid (dry) particulate, liquid particulate (which includes pure substances and aqueous solutions), solids suspended in liquids, and solid-liquid mixtures. It may be microscopic or large enough to be seen by the naked eye. Visibility also depends on the color, quantity, and concentration of the particles present in a given environment.

Safeopedia Explains Dry Particulate

Particulate matter is often categorized according to the size of the particles. For instance, PM10 particles have a maximum diameter of 10 micrometers, while PM2.5 particles have a maximum diameter of 2.5 micrometers. The production of dry particulate is a byproduct of many work processes, such as those involving combustion. Workers exposed to dry particulates can face respiratory and other problems due to inhalation of particles, as well as eye irritation and other health effects.

Safety Measures

Personal protective equipment (PPE) used to protect against dry particulate, such as coveralls, may be less stringent than that used to protect against liquid particulates, depending on the work environment. This is due to the reduced risk that dry particulate will permeate protective material or seep through seams.

Workplace activities that produce dry particulate matter include construction work, mineral processing, various combustion processes, and activities that “unsettle” particulates such as transport over unpaved roads. For instance, coal processing creates large amounts of ash. A major advantage of coal processing using gasification (subjecting it to extremely high heat) instead of combustion is that products resulting from gasification are more dense than combustion products, and thus the dry particulate that results from the process can be more easily filtered.

Exposure Limits

OSHA and other occupational health and safety agencies use exposure limits as a primary method of providing employers with obligations to protect workers from particulate hazards. These limits depend on both the size and toxicity of the individual particulate substance.

Exposure to diesel particulate matter (DPM) is a common source of exposure to dry particulates, especially for workers in construction, mining, and other industries in which diesel-run vehicles are prevalent. OSHA has permissible exposure limits (PEL) for three DPM component gases, while the U.S. Mine Safety and Health Administration directly limits miners’ DPA exposure to an eight-hour time-weighted average of 160 micrograms per cubic meter (μg/m3) measured by total carbon particulates. For situations in which a particulate does not have a specific PEL, it may fall under a “Particulates Not Otherwise Regulated” provision.

It is important for workers to understand the nature of the particulate substances in their workplace, as the risks associated with exposure to dry particulate matter depends on the size, reactivity, and other physical properties of the particulate. The PPE or air scrubbers necessary to prevent or limit exposure are also affected by these properties.


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