Michelangelo's Sistine chapel frescoes are threatened by the effects of too many visitors, experts have warned on Wednesday, as the masterly painted ceiling celebrated its 500th anniversary.

"The anthropic pressure with dust, the humidity of bodies, carbon dioxide produced by perspiration can cause discomfort for the visitors and, in the long run, damage to the paintings," Antonio Paolucci, director of the Vatican Museums, wrote in the Vatican newspaper L'Osservatore Romano.

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"We might limit access, putting a cap on the number of visitors. We will do this, if the pressure from tourism were to increase beyond a reasonable level and if we were to fail in resolving the problem efficiently," Paolucci said.

Some 20,000 people a day –- 5 million a year –- make the Sistine Chapel the most visited room in the world.

"It has a fatal attraction; it is an object of desire, that essential point of arrival for international museum people, for migrants of the so-called cultural tourism," Paolucci said.


Michelangelo Portraits

Many visitors just stare, tranfixed, at one of the most notable artwork ever created. Indeed, Pope Julius II and 17 cardinals reacted in the same way when the vaulted ceiling was revealed in all its blue glory on the Eve of All Saints, 31 October, 1512, during a vesper Mass.

But others are "drunken tourist herds" disrespectful of the unique setting they are visiting, according to leading literary critic Pietro Citati. The "herds" might soon verify the efforts made during a 14-year-long restoration project in the 1990s, he said.

"I believe it will soon be necessary to restore the Sistine Chapel again; and this will go on and on, as long as the vault is filled by heavy human breath," Citati wrote in the daily Corriere della Sera.

At a vespers service which commemorated the unveiling of the frescoed ceiling exactly 500 years ago, Pope Benedict XVI appeared to agree with Citati.

"When contemplated in prayer, the Sistine Chapel is even more beautiful, more authentic. It reveals itself in all its richness," he said.

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A 135 by 44 foot rectangle ringed by 12 windows, the fifteenth-century chapel takes its name from Pope Sixtus IV who commissioned it in 1475-83, to give the Vatican a place for solemn ceremonies.

Indeed, the Pope engaged notable artists such as Botticelli, Ghirlandaio, and Perugino to decorate its walls.

However, the ceiling featured only a blue sky dotted by golden stars. Pope Julius II decided to change the rather dull scene and commissioned the work to a reluctant Michelangelo.

The artist worked on the colorful ceiling frescoes between 1508 and 1512, producing over 300 figures to tell the story of the book of Genesis.

The scenes, including the iconic image of the Creation of Adam in which the fingers of man and God are just inches apart, "radically changed the art world," Paolucci said.

"The ceiling was to become a beacon destined to light the styles of many future generations of artists," he added.

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More than 20 years later, Michelangelo began the Last Judgement fresco behind the altar, creating a chapel Pope John Paul II once called "the sanctuary of the theology of the body."

Indeed, naked angels and saints, prophets and sinners, make a quite graphic backdrop for one of the most solemn moments in the Roman Catholic Church: the election of a new Pope.

This is one of the rare occasions the chapel closes its door to the public.

Since the Sistine is also a consecrated chapel, Paolucci believes all efforts will be made to prevent a restricted access.

He said a specialist company has been asked to design a "new, high-tech, radically innovative" air-purifying system to protect the frescoes from atmospheric damage. The equipment should be ready in a year.

"Our era has not been graced with a new Michelangelo. But we have been graced with technology which allows us to preserve Michelangelo's work for the longest possible time," Paolucci said.

Photo: Creation of Adam – after restoration. Credit: Wikimedia Commons.