U.S. Surgeon General Richard Carmona, who highlighted the dangers of obesity and second-hand smoke, has quit, effective July 31, just a month after he released a comprehensive report on the dangers of secondhand smoke. A letter circulated on Capitol Hill informed Hill staffers of his resignation.

It's unclear who decided it was time for Carmona to go. The former trauma surgeon reportedly plans to return to his home in Tucson, Arizona. Although public health advocates were pleased with his report on secondhand smoking, they were often critical of Carmona for failing to act more forcefully.

"Went out with a whimper, didn't he?" Arizona heath department spokesman Michael Murphy quippted, according the Arizona Daily Star.

"The surgeon general job is one with enormous potential to improve the public health of the entire nation, and several have done just that," said Dr. Sidney Wolfe of Public Citizen. "But Carmona's reign has been a relatively inactive one. It's hard to remember another surgeon general who was so largely invisible as he has been, and that's a tragedy."

Others defended Carmona for doing the best he could in a pro-business administration.

"I think that report is going to turn out to be the nail in the coffin to the tobacco industry," Dr. Georges C. Benjamin, executive director of the American Public Health Association, predicting it will eventually lead to a ban on all smoking in public. He said Carmona served during a "tough time."

Carmona conceded in an Arizona Daily Star interview that he was frustrated by the political pressures that came with the job.

"There were many days ... when science gave way to politics," he said. "What was done was not always my decision."

Carmona spoke too bluntly early in his reign, telling a Congressional committee that all tobacco products should be banned. Observers said he was kept on a tight leash thereafter.

The Bush Administration has lost several of its more outspoken public health and safety appointees. Health and Human Services Secretary Tommy G. Thompson, who campaigned for more healthful eating, was let go after Bush won re-election. Highway safety chief Dr. Jeffrey Runge, who was openly critical of top-heavy SUVs, was moved to a post in the Department of Homeland Security and Consumer Product Safety Commission chair Hal Stratton quit abruptly last month to become a lobbyist.

Carmona's blunt and extensively researched report found that there is no risk-free level of exposure to secondhand smoke and said the the only way to protect nonsmokers from the dangerous chemicals in secondhand smoke is to eliminate smoking indoors.

Secondhand smoke exposure can cause heart disease and lung cancer in nonsmoking adults and is a known cause of sudden infant death syndrome (SIDS), respiratory problems, ear infections, and asthma attacks in infants and children, the report found.

Carmona's four-year term quietly expired Saturday at midnight. His deputy has been named acting surgeon general, leaving the next move to President Bush, who may wait until after the fall elections to name a successor.