I WILL happily explain my comments to R Van Den Heever (Letters, December 4) and apologise for missing his first letter.

When certain construction materials become old and worn, they appear dirty. Take the external chutes at Waterworld which due to the elements, are discoloured – I suspect similar glass-fibre materials would not be used today.

With regard to the internal structure, the chutes were constructed with materials that were obviously not suitable for the environmental climate. On my last visit in 2010, there was evidence of corrosion and oxidisation due to the mix of chlorine and metal construction. Such ‘dirty’ appearance cannot be cleaned.

There are many reports on pool construction materials for pools built in the 1980s and 1990s which explain this. These point to the use of chlorine-based disinfectants which together with contaminants from bathers, produce chloramines – these are thought to be the most important factor in the corrosion of stainless steel in swimming pools.

Add to this that the air temperature in pool halls is generally about one degree centigrade above water temperature and so significantly accelerates corrosion. Consequently the atmosphere of indoor swimming pools is one of the most aggressive to be found in a building environment.

Cllr Tracey Simpson-Laing, deputy leader, City of York Council.