Inhalable and respirable dust
Size-selective fractions of airborne particulate matter defined by sampling conventions: inhalable dust captures particles that may be inhaled through the nose and mouth; respirable dust captures the finer fraction that penetrates to the gas exchange region of the lung.
Local equivalents exist but use different names or numerical thresholds. Do not apply one jurisdiction's values in another.
Also known as
By jurisdiction
UK HSE
“inhalable and respirable dust”Exact equivalentHSE EH40 sets workplace exposure limits for inhalable dust (10 mg/m3 TWA) and respirable dust (4 mg/m3 TWA) as general limits applying where no specific WEL exists. COSHH 2002 requires assessment and control of dust exposure. The particle size definitions follow ISO/CEN conventions.
Irish HSA
“inhalable and respirable dust”Close equivalentIreland follows EU OEL Directives for dust exposure. The Chemical Agents Regulations 2001 apply to inhalable and respirable dust as chemical agents. The OEL values for general dust are set in the Irish Code of Practice for the Chemical Agents Regulations.
US OSHA
“particulates not otherwise regulated”PNORClose equivalentOSHA uses Particulates Not Otherwise Regulated (PNOR) as the category for dusts without a specific PEL: 15 mg/m3 TWA for total dust and 5 mg/m3 TWA for the respirable fraction (29 CFR 1910 Table Z-1). These values are widely regarded as outdated and OSHA recommends following more current NIOSH and ACGIH values.
Practitioner note: The two fractions need different sampling heads and carry different limits. Quoting a result from one against the limit for the other is a common reporting error.