I would like to comment on Cynthia de Giorgio's letter 'No Damage to St John's'. (The Sunday Times, November 30).

First, I had mentioned in my letter that the use of oil-based paint applied to the dado was not the responsibility of the current foundation but was carried out in the past. I was simply using it to illustrate the fact that even the best-intentioned people, like the current foundation, can get it wrong.

With regard to the issue of power washing can I suggest that Ms de Giorgio familiarises herself with the document entitled 'Tender for maintenance and rehabilitation works of the steel truss, cladding and roof water run-off over the main vault at St John's Co-Cathedral'. It clearly states, 'Washing of structure by means of high-pressure fresh water to remove salt, dirt and other contaminants'. Furthermore, in the 'Description of Works' section it states, 'The entire structure is to be cleaned of dirt, paint coatings and surface corrosion by means of grit blasting. Care must be taken not to damage the existing roof membrane over the main vault.'

This is not referring to the renovation of the protective steel roof off-site but to 'the entire structure' on-site. This fact is emphasised by the cautionary warning regarding the existing roof membrane over the main vault.

I feel it is also necessary to point out the health and safety implications of what is proposed in this tender. Both roof lead and lead paint, when subjected to grit blasting, will produce minute airborne lead particles which can result in people in the vicinity of such work, and by that I mean the public, breathing in high levels of lead. It should also be pointed out that when steel structures are exposed to grit blasting it actually turns the surface of the steel into a fine metallic powder.

This serves to confirm that while the foundation has carried out excellent restoration work inside the Cathedral, thanks also to the services of the restorer Sante Guido, it has not been capable of undertaking even a very basic exterior project according to stone restoration best practice and legal public health norms.

How can the public therefore trust the foundation's claims that a huge project such as the excavation of a quarry in the heart of Valletta will be carried out with no damage to the old structures, including the passages, and no impact on the health and well-being of Valletta residents?