Most Americans would not cooperate as officials expect during a terror incident such as a smallpox or dirty bomb attack, U.S. researchers said on Tuesday.

An in-depth survey found that the people do not trust the federal government to take care of them during an attack, and would take many matters into their own hands - endangering themselves and their families.

Only two-fifths of those surveyed would follow instructions to go to a public vaccination site in a smallpox outbreak, and only three-fifths would stay in a building other than their home after a dirty bomb explosion, the study found.

But a little more planning, and working with communities, may help improve emergency plans, leading to better cooperation, the team sponsored by the New York Academy of Medicine found.

If the survey’s predictions are true, said Sherry Glied, chair of the department of health policy at Columbia University in New York, “our plans will fail.”

The study looked at how people would react to two hypothetical scenarios - a smallpox outbreak and a dirty bomb explosion.

Smallpox is a highly infectious virus that killed about 30 percent of victims. It was wiped out in 1979 with global vaccination, and people born after 1972 are not likely to have been vaccinated against it.

A dirty bomb would use a conventional explosion to spread radioactive material.

Current plans call for vaccination as needed during a smallpox attack, and for keeping people inside buildings until the danger from a dirty bomb had passed.

MAKING LOGICAL CHOICES

The researchers conducted in-depth discussions with government and private-sector planners, with community residents from around the country, and did a national telephone survey of 2,545 randomly selected adults.

They found members of the public would not necessarily obey instructions from emergency officials.

“People did not respond irrationally. Rather, they made rational, logical choices,” Glied said.

For instance, many of those surveyed feared they could go to a smallpox vaccination site, get exposed to people who already had smallpox, and then be told they could not safely get the vaccine because they were pregnant, had eczema, AIDS or some other condition.

And when asked to think about a dirty bomb explosion, people said they would try hard to get to their children or other family members, even if told to stay put by authorities.

“Only 59 percent would stay in the building,” said Dr. Roz Lasker, who led the study. “Assuring the safety of people who depend on them is more important than their own safety,” Lasker said.

People have already demonstrated that they will disobey, said Otis Johnson, the mayor of Savannah, Georgia. “In my area, where we have a lot of hurricanes, people ignore hurricane evacuation warnings,” Johnson said.

And only a fraction of the 400,000 health care and emergency workers who have been asked to get a smallpox vaccine have done so, citing worries about side effects.

But these problems could be solved if planners ensured telephone and e-mail communications during an emergency, and if they could ensure that children and other family members would be safe, the researchers said.

The study, published on the Internet at http://www.cacsh.org/eptpp.html, offers strategies for getting better cooperation. For example, black Americans are especially suspicious of federal officials but involving churches and community groups in planning would help overcome their fears.