I find it necessary to comment on James Tyrrell's letter 'Risk of grit blasting the cathedral roof' (The Sunday Times, January 4).

I have to inform Mr Tyrrell that having overseen the maintenance and rehabilitation works of the steel trusses over the main vault at the Co-Cathedral from the contracted firm's side, I can confirm Cynthia De Giorgio's comments (The Sunday Times, November 30) that no power washing was carried out above the Co-Cathedral's vault. Having been discussed by the concerned parties after the tender award, it was agreed unanimously that such a process should be avoided.

Furthermore, all necessary precautions were taken during the course of the works not to expose the delicate roof more than was absolutely necessary. This was a major issue for the architect in charge.

With regards to health and safety and environmental standards, I suggest that Mr Tyrrell check his facts before commenting erroneously that blasting will have an effect on the people in the vicinity.

During the works, reasonable precautions were taken for the fumes resulting from the blasting not to disperse in the general environment. The measures taken were so successful that not one complaint was registered during the course of the works, which is quite unusual in such densely populated surroundings.

My personal opinion after having collaborated with the foundation's management and staff to complete such a delicate operation as the rehabilitation works over St John's is that they are a very able and dedicated team, and it saddens me that members of the public attack their good work without proper factual justification.