Dusts Not Otherwise Specified (Dust NOS) & Occupational Health Issues (2014)

This paper was compiled to give guidance on the assessment, evaluation and control of occupational exposure to dusts not otherwise specified (Dust NOS) with an emphasis on recommending a health‐based occupational exposure limit (OEL). Dust exposures are the bane of many industries, none more so than the tunnelling, construction, mineral extraction and processing industries or those handling or working with dry powders. Low content crystalline silica mineral dust is the most common example of Dust NOS, deriving from rock and soil and being ubiquitous, arising from vehicle traffic, drilling, blasting, crushing, grinding, screening and other such activities. Natural organic dusts free of harmful bacteria or biological toxins and synthetic organic dusts such as polymers may also fit into this classification.

Safe Work Australia (SWA, 2013b) Guidance on the Interpretation of Workplace Exposure Standards for Airborne Contaminants recommends that “Where no specific exposure standard has been assigned and the substance is both of inherently low toxicity and free from toxic impurities, exposure to dusts should be maintained below 10 mg/m3, measured as inhalable dust (8 hour TWA).” While there are workplace exposure standards (WESs) for the various components of dust, such as respirable crystalline silica, and dusts and fumes containing toxins, such as lead, there are no specific WESs for inhalable and respirable substances that are insoluble or poorly soluble in water, of inherently low toxicity and free from toxic impurities, although most State jurisdictions do promulgate limit values for these.

The fact that dust exposures are above the recommended trigger values indicates that controlling such dust is no simple matter. This paper therefore references practical control measures that can be implemented to aid in achieving conformance with the recommended trigger values, thus reducing exposures so far as is reasonably practical. Where suitable controls cannot readily be implemented to adequately reduce exposures below the trigger values, an effective respiratory protection program should be implemented.