Richter: You said they'd be killed publicly.
Robert Langdon: Yes, revenge. For La Purga.
Richter: La Purga?
Robert Langdon: Oh geez, you guys don't even read your own history do you? 1668, the church kidnapped four Illuminati scientists and branded each one of them on the chest with the symbol of the cross. To 'purge' them of their sins and they executed them, threw their bodies in the street as a warning to others to stop questioning church ruling on scientific matters. They radicalized them. The Purga created a darker, more violent Illuminati, one bent on... On retribution.
Robert Langdon: The Illuminati did not become violent until the 17th Century. Their name means 'The Enlightened Ones'. They were physicists, mathematicians, astronomers. In the 1500's they started meeting in secret, because they were concerned about the church's inaccurate teachings. They were dedicated to scientific truth. And the Vatican didn't like that. So the church began to, how did you say it? Oh, hunt them down and kill them.
Camerlengo Patrick McKenna: Open the doors, and tell the world the truth.
Robert Langdon: I need access to the Vatican Archives.
Richter: Access to the Archives is only by written decree by the Holy Father.
Robert Langdon: Fellas, you called me.
Carlo Ventresca: Our church is at war. We are under attack from an old enemy. The Illuminati. They have struck us from within and threatening us all with destruction from their new god's signs.
Claudio Vincenzi: You spent your whole life searching for symbols like the one you now hold in your hand. How long are we going to pretend you have not already decided to come?
Chosen answer: In reality, they would have perished from CO2 poisoning long before the room ran out of breathable oxygen causing them to simply suffocate. Without knowing the exact dimensions of the room it is impossible to give any time more specific than "several hours" for this to happen in a room as big as that one appeared to be.
Phixius ★
I just re-watched the movie, and as Langdon and Vittoria enter the room, it's mentioned to them that the oxygen levels are always kept at a bare minimum to protect the ancient tomes and documents stored there. That helps to answer my own question about why Langdon and the cop were so quickly affected when the power was shut off.
raywest ★