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The Management of Health and Safety is an important aspect of all conservation techniques and this is especially true of relatively new techniques such as laser cleaning. Issues to consider include the following:
What risks exist:
Viewing of laser radiation either directly or by reflection
Viewing of secondary light emission from the cleaning process
Inhalation of waste products from the cleaning process
Exposure of skin to direct laser radiation.
Control measures: Appointment laser safety supervisors:
Laser safety supervisors should be appointed to advice on safety matters and to authorise users.
Authorisation and training of users:
Only authorised users of the laser system are permitted. Attendance at a laser safety awareness course is required for attainment of authorised user status. All users must have a knowledge of the potential risks of lasers and laser cleaning. All users must have an opthalmic examination before first use of the laser.
Provide a room for laser use:
A room should be set aside for laser use. The laser footprint is approximately 1m x 0.6m with a working distance of 1-2m from the laser to the object being cleaned. The room should therefore be of sufficient size to house the laser and a typical object [say 2m maximum dimension] and any protective packaging as well as an appropriate extraction system (see below). The room should therefore be approximately 15-20m2 in size and should also be:-
(i) light tight
(ii) fitted with a visible warning notice and/or device
(iii) interlocked so that the laser is shutdown if the door is opened
(iv) kept as free of clutter as possible.
(v) Fitted with a minimum of reflecting surfaces.
(vi) well lit
(vii) equipped with laser safety information clearly displayed
Working outside the laser room:
If work should be required outside the dedicated laser room, an area for laser use must be created and clearly defined. This must be such that the laser beam is confined within the area. The user must seek the advice of, and gain the approval of a laser safety supervisor before any laser use takes place.
Keys must be removed from the laser when the laser is not in use and stored in a separate area to prevent non authorised personnel from switching the laser on.
Use of protective eye wear:
Appropriate safety eye wear must be worn at all times by laser users and any viewers. It is the responsibility of the operator to ensure that safety eye wear is being worn by all present before laser use begins.
A high standard of general illumination is required at all times so that the pupil of the eye remains as small as possible.
Suitable extraction should always be used to remove the waste products of laser cleaning with venting external to the laser room if possible. Face masks should also be worn at all times when cleaning is carried out.
Frequent breaks must be taken while laser cleaning. It is recommended that a break of at least 5 minutes should be taken every 30 minutes. It is also recommended that a total of no more than 3.5 hours of laser cleaning should be undertaken in a 24 hour period. Work should cease immediately if any signs of discomfort appear, medical attention should then be sought if symptoms persist.
Comments: The laser cleaning technique is relatively new and the long term effects are not yet known. Any risks due to the effects of laser cleaning may vary between individuals and these control measures should be viewed as guidelines only. The laser safety supervisors will seek to monitor and amend the safety guidelines as new information becomes available.