VATICAN CITY - The Vatican Museums chief warned that dust and polluting agents brought into the Sistine Chapel by thousands of tourists every day risk one day endangering its priceless artworks.

Antonio Paolucci told the newspaper La Repubblica in comments published Thursday that in order to preserve Michelangelo's Last Judgment and the other treasures in the Sistine Chapel, new tools to control temperature and humidity must be studied and implemented.

Between 15,000 and 20,000 people a day, or over 4 million a year, visit the chapel where popes get elected, to admire its frescoes, floor mosaics and paintings.

"In this chapel people often invoke the Holy Spirit. But the people who fill this room every day aren't pure spirits," Paolucci told the newspaper.

"Such a crowd ... emanates sweat, breath, carbon dioxide, all sorts of dust," he said. "This deadly combination is moved around by winds and ends up on the walls, meaning on the artwork."

Paolucci said better tools were necessary to avoid "serious damage" to the chapel.

Visitors who want to see Leonardo da Vinci's "The Last Supper" in Milan must go through a filtration system to help reduce the work's exposure to dust and pollutants. This has made seeing da Vinci's masterpiece more difficult: 25 visitors are admitted every 15 minutes.

The Sistine Chapel, featuring works by Michelangelo, Botticelli and Perugino, underwent a massive restoration that ended in the late 1990s. The restoration was controversial because some critics said the refurbishing made the colors brighter than originally intended.