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Hi I have seen dust monitors measure dusts to PM10 and PM2.5 measurements. However, normal dusts outsdie of EH40 have Work exposure limits of 10mg.m-3 inhalable and 4mg.m-3 respirable.
How do the PM values relate to the WELs? It all looks very confusing. I wouldnt mind getting an instrument to measure to PM10 and PM2.5 but need to know how it relates to the mg.m-3 values we get through annual air monitoring Regards
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Hm, my study notes say that up to 7 microns is respirable and up to 10 microns (so PM10) is inhalable.
Not sure that really helps you though.
I've always had dust measurements done by an occupational hygienist who is able to interpret the results.
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Dusts? PM is Particulate Matter the number refers to the size in microns. The problem with particulate matter is that it sources are a lot broader than dusts. Try not to be distracted in the workplace - EH40 is occupational exposure measured in mg/m3 - if you are enacting workplace controls a Particulate Matter meter currently has no value. If you are chasing PM values stand by to be very dissappointed as there are so many sources you don't stand a snowflake in hell chance of controlling. Certain metro mayors believe that switching to EV and congestion charging will reduce PM - problem is those EV with reinforced tyres and electrical braking also create significant PM in their own right.
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Rank: Super forum user
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Dusts? PM is Particulate Matter the number refers to the size in microns. The problem with particulate matter is that it sources are a lot broader than dusts. Try not to be distracted in the workplace - EH40 is occupational exposure measured in mg/m3 - if you are enacting workplace controls a Particulate Matter meter currently has no value. If you are chasing PM values stand by to be very dissappointed as there are so many sources you don't stand a snowflake in hell chance of controlling. Certain metro mayors believe that switching to EV and congestion charging will reduce PM - problem is those EV with reinforced tyres and electrical braking also create significant PM in their own right.
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Hi David I think in simple terms you could work on the basis that you consider PM values when considering public air quality but stick to WELs when it comes to occupational exposure. As Roundtuit indicates, Particulate Matter encompasses more than just dust.
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https://www.gov.uk/guidance/monitoring-ambient-air-particulate-matter
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Rank: Super forum user
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The PM bit stands for Particulate Matter and PM10 means anything which has an average diameter less that 10 μm and PM2.5 means it has a diameter of less than 2.5 μm. I am not sure where this definition comes from. The legal definition of “inhalable dust” and “respirable dust” is to be found in regulation 2 of COSHH, which is in turn defined in BS EN 481 1993. I don’t have a copy of that standard. EH40 para 13 states that “For the purposes of these limits, respirable dust and inhalable dust are those fractions of airborne dust which will be collected when sampling is undertaken in accordance with the methods described in MDHS14/4 General methods for sampling and gravimetric analysis or respirable, thoracic and inhalable aerosols.” MDHS14/4 refers back to BS EN 481 1993. I assume that the occupational hygienist, that Kate mentioned, knows what all this means and that’s probably why it’s best left to them to produce a report.
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In UK occupational hygiene terms: PM values (e.g., PM₂.₅, PM₁₀) refer to particulate matter concentrations in air, usually given in micrograms per cubic metre (µg/m³), and are more common in environmental and air quality monitoring (DEFRA, WHO, EPA contexts) than in workplace exposure limits. They measure airborne particle size fractions: - PM 10 – particles ≤10 µm in diameter (respirable + inhalable fraction).
- PM 2.5 – particles ≤2.5 µm (fine fraction, more likely to penetrate deep into the lungs).
WELs (Workplace Exposure Limits), from EH40/UK HSE, are legal occupational limits for specific substances or dusts, usually given in mg/m³ over an 8-hour TWA or 15-minute STEL.
For dusts, WELs are usually defined for inhalable and respirable fractions: - Inhalable dust: WEL = 10 mg/m³ (8-hr TWA)
- Respirable dust: WEL = 4 mg/m³ (8-hr TWA)
How they relate - PM values are environmental measurements, size-based, without reference to specific toxicology — they tell you how much dust of a certain aerodynamic size is present.
- WELs are substance-specific legal limits in workplaces, based on toxicology and health effects.
- You can’t directly compare PM2.5 in µg/m³ to WEL mg/m³ without unit conversion and an understanding of which particle fraction the WEL covers.
- In practice, PM 2.5 is roughly equivalent to a subset of the respirable fraction, while PM₁₀ overlaps with the inhalable fraction.
- Environmental PM limits (e.g., WHO PM₂.₅ annual guideline: 5 µg/m³) are much lower than workplace WELs, because WELs apply to healthy adult workers over a career, not the general public.
Simples... :)
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