The Sistine Chapel has been fitted with detectors to check for pollution from its millions of visitors every year that could harm priceless frescoes by Michelangelo and Botticelli.

Vatican Museums director Antonio Paolucci explained in the Holy See’s official daily, Osservatore Romano, on Thursday that the initiative was in order to update the building’s air conditioning and ventilating system.

"We will make every effort to keep it open, with the conviction that it is possible to do so without creating a risk for the frescoes," Paolucci said.

Paolucci explained that the unsightly detectors put in place this summer measure temperature, humidity, chemicals as well as currents of air.

"It was necessary to understand the dynamics of the pollution," he said.

Thirty-six of the detectors are suspended and 14 others are fitted in other parts of the chapel, which is covered in paintings on the walls and ceiling.

The sensor data is then matched with statistics on the number of visitors at any one time obtained through thermal cameras fitted on the doors.

The Sistine Chapel is an artistic masterpiece and a central place for Roman Catholicism as it is there that cardinals meet in conclave to elect a new pope.

The chapel receives more than four million visitors every year.

Last year, scientists discovered a high quantity of particles on the walls that could cause chemical reactions that would harm the paintings.

The ventilation system by a company called Carrier was installed after the completion of the last major restoration project on the chapel in 1993.