But Hassan, who has both British and Iraqi citizenship, remained.
She continued to wake up early every morning to arrive at the west Baghdad office of CARE by 7:30 a.m. And that is exactly where the kidnappers were waiting for her yesterday.
Her husband, Tahseen Hassan, described her capture to Reuters this way.
"The kidnapping happened as my wife got near her place of work. Two cars came, one from the front and the other from behind. They stopped the car and removed the driver and the guard. They then took the car and went off in an unknown direction. This is what we heard from the people of the organization (CARE) because the incident occurred near the organization," Tahseen Hassan said.
So far, almost nothing is known about who kidnapped Hassan or their motives.
A previously unheard of group sent a grainy videotape to the Qatar-based satellite channel Al-Jazeera yesterday showing Hassan in captivity. The videotape displays Hassan's identity cards and shows her seated on a sofa, looking anxious.
But the videotape includes no details about the hostage-takers themselves and sets forth no political or monetary demands.
At CARE, Hassan directed the operations of 60 Iraqi professionals, rebuilding health centers, providing medical supplies to hospitals, and restoring clean water supplies.
Joost Hilterman, a regional expert with the International Crisis Group based in Amman, describes Hassan as someone devoted to helping the Iraqi poor despite the dangerous security situation.
"She stayed on because Iraq was her country and she wanted to help the people. She didn't even have armed guards to protect her. She felt safe enough [despite] the current circumstances and confident in the kind of work she was doing," Hilterman said.
Hilterman remembers meeting Hassan immediately after the U.S.-led invasion that toppled Saddam Hussein in April last year.
He says that she was one of the first voices inside Iraq to warn that the breakdown of law and order in the wake of the invasion was directly fueling resentment of the occupation among ordinary citizens.
"She was very much in tune with how Iraqis felt. There was a lot of discontent emerging very quickly about the chaos in the streets and she gave voice to that and, I think, very courageously because at that time there was euphoria in the United States over the removal of the regime, of course, and very little appetite to listen to voices, critical voices, that however said the right thing," Hilterman said.
Hassan came to Iraq three decades ago after meeting her husband in London when he was working with Iraqi Airways. She joined CARE in 1991.
British Prime Minister Tony Blair yesterday called Hassan a respected figure in Iraqi society.
"This is someone who has actually lived in Iraq for 30 years. This is someone who is immensely respected, married to an Iraqi, someone who is doing her level best to help the country and I think it shows you the kind of people we are up against, that they were prepared to kidnap somebody like this," Blair said.
Hassan's kidnapping comes just two weeks after a militant group beheaded British national Kenneth Bigley.
The group -- led by Al-Qaeda loyalist Abu Mus'ab al-Zarqawi -- killed Bigley after demanding U.S. and British forces free all women prisoners held in Iraq.
Washington and London dismissed the demand as ill-informed, saying they hold only three prominent females who worked on Hussein's weapons development programs.
Since a rash of kidnappings of foreigners began in Iraq in April, more than 150 people have been seized. About 35 have been killed.
So far, none of the seven foreign women known to have been kidnapped were killed. They include two Italian humanitarian workers set free last month after three weeks in captivity.