New York They dug in the toxic World Trade Center dust for survivors, and later for the dead. Their feet were burned by white-hot debris. But unlike thousands of others who toiled at ground zero after Sept. 11, these rescue workers aren't sick.
Scientists have spent years studying the health of search-and-rescue dogs that nosed through the debris at ground zero, and to their surprise, they have found no sign of major illness in the animals.
They are trying to figure out why this is so.
"They didn't have any airway protection, they didn't have any skin protection. They were sort of in the worst of it," said Cynthia Otto, a veterinarian at the University of Pennsylvania, where researchers launched a study of 97 dogs five years ago.
Although many ground zero dogs have died - some of rare cancers - researchers say many have lived beyond the average life span for dogs and are not getting any sicker than average.
Owners of the dogs dispute the findings, saying there is a definite link between the toxic air and their pets' health.
Otto has tracked dogs that spent an average of 10 days after the 2001 terrorist attacks at either the trade center site, the landfill in New York where most of the debris was taken, or the heavily damaged Pentagon.
As of last month, she said, 30 percent of the dogs deployed after Sept. 11 had died, compared with 22 percent of those in a comparison group of dogs who were not pressed into service. The difference was not considered statistically significant, Otto said.
A separate study, to be published soon by a doctor at New York's Animal Medical Center, focused on about two dozen New York police dogs, and comes to similar conclusions.
The results have baffled doctors. A study released last month found that 70 percent of the people who worked at ground zero suffer severe respiratory problems; scientists thought that the dogs might have similar health problems.
The dogs' owners and scientists have many theories why dogs aren't showing the same level of illness as people. Their noses are longer, possibly serving as a filter to protect their lungs from toxic dust and other debris, they say. The dogs were at the site an average of several days, while many people spent months cleaning up after the attacks.