Introduction to Health and Safety at Work

Introduction to Health and Safety at Work
234
The over-riding requirement for any hazardous 
substance, which has a WEL from Group 1, is to reduce 
exposure to as low as is reasonably practicable.
Finally, there are certain limitations on the use of the 
published workplace exposure limits:
➤
they are specifi cally quoted for an 8 hour period (with 
an additional STEL for many hazardous substances). 
Adjustments must be made when exposure occurs 
over a continuous period longer than 8 hours
➤
they can only be used for exposure in a workplace 
and not to evaluate or control non-occupational 
exposure (e.g. to evaluate exposure levels in a 
neighbourhood close to the workplace, such as a 
playground)
➤
WELs are only approved where the atmospheric 
pressure varies from 900 to 1100 millibars. This could 
exclude their use in mining and tunnelling operations
➤
they should also not be used when there is a rapid 
build-up of a hazardous substance due to a serious 
accident or other emergency. Emergency arrange 
ments should cover these eventualities.
The fact that a substance has not been allocated a WEL 
does not mean that it is safe. The exposure to these 
substances should be controlled to a level to which 
nearly all of the working population could be exposed 
all the time without any adverse effects to their health. 
Detailed guidance and references are given for such 
substances in the HSE ACOP and guidance to the 
COSHH Regulations (L5).
HSC has publishing a revised ACOP and EH40 to 
include these changes. More information on the latest 
COSHH Regulations is given in Chapter 17.
14.8.3 Sources of information
There are other important sources of information avail-
able for a COSHH assessment in addition to the HSE 
Guidance Note EH40.
Product labels
include details of the hazards associated 
with the substances contained in the product and any 
precautions recommended. They may also bear one or 
more of the CHIP hazard classifi cation symbols.