|
|
 WELS Limits monitoring
1/10/2007
Employers have a duty under the Control of Substances Hazardous to Health (COSHH) Regulations to control workplace exposures to hazardous substances. Nearly all industry regulated by the Health and Safety Executive (HSE) is affected in some way by the COSHH regulations, for example those using paints in the coating of manufactured products, solvents in the printing industries, silica and metals used in foundries, wood dust in furniture production and disinfectant type chemicals used to clean medical instruments in hospitals. Under regulation 7 of the COSHH regulations, it is stated that control of exposure may only be treated as adequate “if any workplace exposure limit approved for that substance is not exceeded.” Therefore employers have a duty to ensure each of their employees is not exposed to any concentration of substance in excess of the workplace exposure limit for that substance.
The workplace exposure limit (WEL) value is expressed as a time weighted average (TWA) and there are two variations, the long term exposure limit (LTEL) which is the maximum exposure permitted over an 8-hour period and the short term exposure limit (STEL) which is the maximum exposure permitted over a 15-minute reference period. The LTEL is designed to protect the workforce from concentrations of contaminant, which over a large period of time could cause long term chronic ill health effects. Whereas the STEL exposure limit is designed to protect against immediate acute ill-health effects.
Workplace exposure limits are approved by the Health and Safety Commission (HSC) acting on advice given from the Advisory Committee on Toxic Substances, (ACTS) which in turn act on scientific and technical advice given by Working Group on Action to Control Chemicals (WATCH).
Due to the large amount of chemical compounds used in the workplace there is insufficient information available on many of these to warrant quantifiable exposure limits to be in place. Subsequently not all chemicals used in the workplace have WEL values. New substances are added and existing ones can be revised and are published in new additions or supplements to the Health and Safety Executives EH40 booklet.
Brand New WEL Limits Due 1st October 2007
In October 2007 the European Commission’s 2nd Directive on Indicative Occupational Exposure Limits will be implemented in Great Britain. The Directive requires member states to set domestic exposure limits for a list of 33 substances. Member States of the European Union (EU) are obliged to take account of Occupational Exposure Limit Values (OELVs) developed by the EU when setting national limits, and must set a national limit for all the substances listed in the Directive. As a result a number of brand new and revised WEL values are to be introduced.
For example the WEL value for Diethylamine, used in the production of resins, rubber and dyes is to be halved from 10mg/m3 to 5mg/m3, 8hr TWA. As a result, where Diethylamine is in use, COSHH assessments may need to be revised. For example, where operative exposure may have been just over 50% of the value under the old limit, it would now be over of WEL value when considering the revised limit.
Similarly, the WEL value for nitrobenzene used in the manufacture of polishes and insulators has been reduced from 1mg/m3 to 0.2mg/m3, i.e. a five fold reduction. Under the previous limits an operative who was exposed to around a quarter of the WEL value, would now be exposed to levels above the permitted limit thus a COSHH re-assessment is needed and action would need to be taken to reduce exposure.
Where new substances are added for the first time, it is then the duty of the employer under the COSHH regulations to ensure these limits are not reached or exceeded. For example in October, Pentane, extensively used in laboratories, will be assigned a WEL value for the first time, and thus employers may wish to undertake monitoring to ensure the WEL value is not exceeded.
For a full list of new and revised WEL values see the supplement to EH40/2005 on the HSE website. www.hse.gov.uk/legislation
How Envirocare can help you
In order to assist you in preparing an up to date COSHH assessment, the most effective way of assessing exposure levels to substances in the workplace is by portable air sampling. A popular way of doing this is by drawing a known quantity of air through a sorbent tube, which is then analysed for contaminants known to be used in the process. Samples can be fitted to operatives over the course of a day to determine personal exposure. Measurement should be carried out at regular intervals, when processes change, when new plant or materials are introduced, or when new information comes to light regarding the substances used, such as a new or revised WEL.
Envirocare can offer a range of air monitoring services to suit your needs. Please contact our Health & Safety Manager. Andrea Beswick for further information on 01274 738668 or andrea@envirocare.org. For information please view our website www.envirocare.org
|
Email: .jpg)
