LONDON (AlertNet) - More aid workers were killed worldwide by deliberate violence than accidents or illness in the past three years, according to researchers in the United States trying to measure if the humanitarian world is more dangerous than it used to be.

A lot of aid workers say that in the climate following the September 11, 2001 attacks in the United States there's a higher risk of humanitarians being targeted for attack in some countries because they are perceived as Westerners, while others shrug off the threat and say they're more likely to get hurt in a car crash.

"Security is a priority concern for aid workers," said researcher Elizabeth Rowley. "But there's a range of definitions. People have different ideas of what's risky."

It's hard to measure what's really going on in the field, but after more than three years of research, Rowley and other academics at the Center for Refugee and Disaster Response at the Johns Hopkins Bloomberg School of Public Health in Baltimore say most shootings, ambushes and rapes happen to aid workers on the way to and from projects.

Here's what they found:

Intentional violence caused 60 percent of all deaths.

When it came to deaths, medical evacuations and hospitalisations, intentional violence was the culprit 25 percent of the time.

About 65 percent of intentional violence happened to staff on their way to or from project sites, rather than in their homes or offices.

Most - 71 percent - of cases of intentional violence did not involve theft.

National staff were the target of 63 percent of intentional violence, and also accounted for 77 percent of intentional violence-related deaths.

56 percent of cases of intentional violence resulted in death, with 22 percent leading to hospitalisation and 22 percent requiring evacuation.

Small arms were used in at least 56 percent of the reported cases.

The researchers say local staff from countries where humanitarian organisations work are more likely to be targeted than international aid workers from abroad.

Their survey examined data from 20 aid agencies - eight European and 11 North American -- between September 2002 and December 2005, categorising the events which resulted in death, hospitalisation or medical evacuation.

Researchers distinguished deliberate violence from accidents - ranging from people falling off chairs to staff hurt by drunk drivers - and all kinds of illnesses.

Rowley said she was surprised that intentional violence had killed more people than traffic accidents, which aid workers often assume is their highest risk.

She said researchers wanted to analyse whether training for hostile environments - becoming more common in many aid organisations - had an impact in preparing staff or reducing casualties.

To say for sure whether aid workers are being targeted more, researchers say they need to build up comparable data year after year and factor in the number of aid workers potentially at risk in the field.

"There's anecdotal observation that humanitarian work is becoming riskier over time," Rowling said. "But nobody has actually measured it over time."

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