New workplace exposure limits were implemented for 31 substances from 21 August 2018. The updates in the latest edition of the EH40 reintroduced the biological monitoring guidance values in for:
- Chlorobenzene – 5 mmol 4-chlorocatechol/mol creatinine in urine – Post shift
- Isocyanates (applies to HDI, IPDI, TDI and MDI) – 1 μmol isocyanate-derived diamine/mol creatinine in urine – At the end of the period of exposure
- 4,4-methylenedianiline (MDA) – 50 μmol total MDA/mol creatinine in urine Post shift for inhalation and pre-shift next day for dermal exposure
What are the new and revised workplace exposure limits (WELs)?
There are 31 substances in EH40 that have been added or revised (below).
Most notably, new workplace exposure entries for nitrogen dioxide and nitrogen monoxide, with a reduction in the WEL for the existing carbon monoxide limit, will influence the assessment of exposure to Diesel Engine Exhaust Emissions (DEEEs).
Other notable compounds that have been revised include the new short-term exposure limit for sulphur dioxide – present vehicle emissions– and diacetyl, a chemical used in food and manufacturing industries.
On 21 August 2018, the European Commission’s fourth Directive on Indicative Occupational Exposure Limit Values (2017/164/EU) was implemented in Great Britain and Northern Ireland. This Directive requires Member States of the European Union to introduce domestic occupational exposure limits for the substances listed in the Annex to the Directive.
Additionally, the level of the domestic limit must take account of the indicative occupational exposure limit values (IOELVs). The Health and Safety Executive has approved new and revised workplace exposure limits (WELs) required to implement the fourth IOELV Directive.
There were new entries for the following substances:
- 2-ethylhexan-1-ol
- Acetic acid
- Acrylic acid
- Amitrole
- But-2-yne-1,4-diol
- Diacetyl
- Glycerol trinitrate
- Methyl formate
- Nitroethane
- Nitrogen dioxide
- Nitrogen monoxide
- Sulphur dioxide
- Hydrogenated terphenyl
- Tetraethyl orthosilicate
New 8-hour time-weighted averages (TWAs) were introduced for:
- 2-ethylhexan-1-ol
- Amitrole
- But-2yne-1,4-diol
- Calcium dihydroxide (respirable fraction)
- Calcium oxide (respirable fraction)
- Hydrogen cyanide (as cyanide)
- Nitrogen monoxide
- Tetraethyl orthosilicate
New 8-hour TWA and short-term exposure limits (STELs) were introduced for the following substances:
- Acetic acid
- Acrylic acid
- Diacetyl
- Glycerol trinitrate
- Methyl formate
- Nitrogen dioxide
- Sulphur dioxide
- Hydrogenated terphenyl
New skin notations have been added for the following substances:
- 1,4-dichlorobenzene
- Glycerol trinitrate
- Methyl formate
- Tetrachloroethylene
The following substances required reductions to the existing WELs:
- 1,4-Dichlorobenzene
- Acrolein
- Bisphenol A
- Carbon monoxide
- Carbon tetrachloride
- Manganese and inorganic manganese compounds
- Methylene chloride (dichloromethane)
- Potassium cyanide (as cyanide)
- Sodium cyanide
- Tetrachloroethylene
- Vinylidene chloride
A STEL was introduced for:
- Acetic acid
- Acrylic acid
- Calcium dihydroxide
- Calcium oxide
- Carbon tetrachloride
- Diacetyl
- Diphenyl ether
- Glycerol trinitrate
- Lithium hydride
- Manganese and inorganic manganese compounds
- Methyl formate
- Nitroethane
- Nitrogen dioxide
- Potassium cyanide (as cyanide)
- Sodium cyanide (as cyanide)
- Sulphur dioxide
- Hydrogenated terphenyl
- Vinylidene chloride
The existing 8-hour TWA WEL was removed and the IOELV STEL was adopted for:
- Lithium hydride
Why is Air Monitoring required?
The reason that air monitoring is required, is that hazardous substances, (particles, chemicals, biological agents) in a workplace can be a source of adverse health effects. The measurement of such substances in the air, will reveal if workers are exposed to significant quantities.
Air monitoring should be part of a full occupational hygiene assessment, as this also looks at the working practices and control measures. It brings it all together, to assess risk and provide useful recommendations for the workplace.
From this information, and the observations made during the survey, an assessment of the risk level can be made.