Outside of health and safety, I have an interest in old buildings and their conservation. A couple of years ago, on a field visit as part of a course I was doing, I went on a tour of the stained glass conservation workshops at Salisbury Cathedral. Here they repair and refabricate stained glass panels for the historic windows in the cathedral and for other churches in the surrounding area. The coloured glass pieces are held together by lead strips, cast, extruded, cut, bent and soldered together by a small team of craftsmen.
As I was reasonably familiar with the health effects of lead from a theoretical and control point of view, and from dealing with old steel structures painted with lead based paints, I was expecting there to be a very onerous control system in place to prevent exposure – perhaps a sealed environment with extract ventilation, full body suits and respirators – something like the environment needed for asbestos removal. Far from it, it was much like any conventional craftsman’s workshop.
Substitution with an alternative material is not an option. The reason for the workshop’s existence is to maintain the historic character of the windows by preserving the original material wherever possible.
The main risk was from inhalation, either of dust or fume, and their processes were designed to eliminate this. To eliminate dust, there was no drilling. Cutting was done by a guillotine, or for more detailed work, with a craft knife, so no sawing. To make the extruded strips, lead was melted and cast, with the temperature controlled so that it did not get hot enough to generate fume. LEV (local exhaust ventilation) was not used when soldering. Soldering generally takes place at a temperature of around 380C and significant lead fume is only generated above 450C.
The lower risk was from ingestion, for which the main precautions were around hygiene – plenty of hand washing, and care to avoid touching the face with dirty hands or clothing. Protective outer clothing was changed before leaving the workshop, and laundered daily. There was of course, no eating, drinking or smoking in the workshop. Any waste (lead scraps, and cleaning cloths) was carefully collected and dealt with as hazardous waste, as was the residue from daily vacuuming. No respiratory protection was needed, and no PPE apart from overalls and aprons. A good example of using the hierarchy of control effectively.
Skin absorption is only a risk from lead alkyls or naphthenate (as in leaded petrol), not from metallic lead.
The effectiveness of this regime had been proven with long term air sampling and blood tests for absorbed lead. Workers were subject to routine health surveillance, but none of them had had elevated levels of lead detected. Although not a public area, occasional escorted visitors were able to walk around freely, as long as they did not touch anything.
Somewhat inevitably, this visit led to the drafting of a question for one of the NEBOSH.
For further information on health risks from lead, and guidance on control of exposure to lead at work, the HSE Approved Code of Practice and accompanying guidance (Series code L132) is available free on line from :- http://www.hse.gov.uk/pubns/books/l132.htm