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18
Safety Limits
The maximum permissible concentration, related to average concentrations for a normal working day, is
100 parts per million (p.p.m.). This refers to air-borne concentrations of the solvent and is related to
conditions under which it is believed that nearly all workers may be repeatedly exposed day after day,
without adverse effect.
In this context it should be noted that perchloroethylene may be detected by smell at 50 p.p.m., which
is well below the threshold limit.
Solvent Loss
Whilst most machines are designed to clarify and recirculate the solvent used, inevitably a certain
amount is lost, principally
(a) to the atmosphere — during the "aeration" cycle, this loss may be reduced by up to 80% by the use
of a solvent recovery unit. Solvent discharged to the atmosphere is, in any event, usually
substantially diluted and measurements taken within six feet of the exhaust point of a typical
installation have indicated that (even without the use of a carbon recovery unit) a concentration of
25 p.p.m. was rarely exceeded.
(b) in the garments cleaned — with an efficient plant, properly operated this should rarely exceed 4
p.p.m.
(c) in sludge, lint, etc. from filters.
Legal Provisions
An unusual anomaly exists whereby similar equipment may be installed in different premises which are
subject to varying legal requirements, i.e.
(a) the premises may be a FACTORY subject to the requirements of the Factories Act, 1961, or
(b) the premises may not be such as to constitute a factory but may be subject to the Offices, Shops and
Railway Premises Act, 1963; alternatively
(c) the premises may not be subject to the Factories Act, 1961, or the Offices, Shops and Railway
Premises Act (i.e. where persons are self-employed or total hours worked are less than 21 per week).
The potential hazards are, nevertheless, the same in each case.
Dry-cleaners constituting a FACTORY
Apart from the general powers available which control factors affecting the health and welfare of
employees, specific additional powers exist:-
(a) restricting the siting of plant, i.e. processes which are liable to give off fumes may not be sited in
underground rooms,
(b) to require removal of fumes likely to be injurious or offensive to employed persons.
Dry-cleaners constituting a SHOP subject to the Offices. Shops and Railway Premises Act, 1963
No specific powers exist controlling siting of plant or removal of injurious fumes, although the latter
may well be dealt with under Section 7, which requires "effective and suitable" ventilation of all rooms in
which persons are employed to work.
Section 22 of the Act contains, however, strong powers to deal with dangerous conditions and practices.
Where an inspector of the enforcing authority considers that any part of premises, or any machinery or
appliances in them, or any operations carried out in them, are so dangerous that their continued use is a risk
to safety or health, there is provision for a magistrate's court to make an order prohibiting their use or
continuance to the extent necessary, until steps have been taken to remedy the source of danger.