|Cathedral closed until further notice|
St Paul's safer from pollution than at any time in its history
10 October 2012
A 30-year project to monitor erosion to the stonework of St Paul’s has concluded the risk of damage by pollution is as low as it has ever been in the Cathedral’s history.
Scientists from the universities of Portsmouth, Oxford, Sussex and Cambridge carried out the research, the longest-ever study of erosion rates on a single building, between 1980 and 2010. The research has been published in the journal, Atmospheric Environment.
With monitors placed on the building during that time, they found that sulphur dioxide levels – responsible for acid rain – have fallen by 95 per cent, due largely to a decrease in industry and power generation in central London.
Acid rain is now responsible for just a fraction of one per cent of the damage to the white Portland limestone used to build St Paul’s, and the rate of erosion at the Cathedral is now dominated by natural rainfall.
Robert Inkpen, of the University of Portsmouth, said: "We were surprised that the results were so compelling – the drop in erosion over 30 years is quite dramatic and the data clearly illustrates erosion rates have now fallen to levels you would expected with just natural rainfall.”
The research team began their study a year before the closure of Bankside Power Station (now the Tate Modern art gallery) in 1981. It had been generating electricity for 29 years emitting carbon dioxide, sulphur dioxide and nitrous oxide. In the year it opened, 1952, pollution across the city was commonplace and London’s ‘great smog’ of that year saw thousands die due to pollution.
Dr Inkpen said: "The cocktail of gases emitted by the power station and the fact it was directly across the river from St Paul’s means it is highly likely it was responsible for the more modern erosion of the cathedral.
"But it is by no means the only problem. London’s growth as a major international city since Wren’s day and the pollution produced by the industrial and commercial activity of a thriving city as well as domestic smoke have all contributed to producing high erosion rates in the past. Previous research by the team suggested that between 1710 and 1980 the yearly erosion rate was at least double the current erosion rate.”
The researchers have continued studying erosion and surface change rates at the Cathedral and will report their next findings in 2020.