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SAFETY AND LOSS PREVENTION
Fuller details of the methods used for toxicity testing, the interpretation of the result
and their use in setting standards for industrial hygiene are given in the more specialised
texts on the subject; see Carson and Mumford (1988) and Lees (1996).
Control of substances hazardous to health
In the United Kingdom the use of substances likely to be harmful to employees is covered
by regulations issued by the Health and Safety Executive (HSE), under the Health and
Safety at Work Act, 1974 (HSAWA). The principal set of regulations in force is the
Control of Substances Hazardous to Health regulations, 2002; known under the acronym:
the COSHH regulations. The COSHH regulations apply to any hazardous substance in
use in any place of work.
The employer is required to carry out an assessment to evaluate the risk to health,
and establish what precautions are needed to protect employees. A written record of the
assessment would be kept, and details made available to employees.
A thorough explanation of the regulations is not within the scope of this book, as they
will apply more to plant operation and maintenance than to process design. The HSE
has published a series of booklets giving details of the regulations and their application
(see www.hse.gov.uk/pubns). A comprehensive guide to the COSHH regulations has also
been published by the Royal Society of Chemistry, Simpson and Simpson (1991).
The designer will be concerned more with the preventative aspects of the use of
hazardous substances. Points to consider are:
1. Substitution: of the processing route with one using less hazardous material. Or,
substitution of toxic process materials with non-toxic, or less toxic materials.
2. Containment: sound design of equipment and piping, to avoid leaks. For example,
specifying welded joints in preference to gasketed flanged joints (liable to leak).
3. Ventilation: use open structures, or provide adequate ventilation systems.
4. Disposal: provision of effective vent stacks to disperse material vented from pressure
relief devices; or use vent scrubbers.
5. Emergency equipment: escape routes, rescue equipment, respirators, safety showers,
eye baths.
In addition, good plant operating practice would include:
1. Written instruction in the use of the hazardous substances and the risks involved.
2. Adequate training of personnel.
3. Provision of protective clothing.
4. Good housekeeping and personal hygiene.
5. Monitoring of the environment to check exposure levels. Consider the installation
of permanent instruments fitted with alarms.
6. Regular medical check-ups on employees, to check for the chronic effects of toxic
materials.

9.3.2. Flammability
The term “flammable” is now more commonly used in the technical literature than
“inflammable” to describe materials that will burn, and will be used in this book. The
hazard caused by a flammable material depends on a number of factors: