NEW ORLEANS — The putrid air rising from New Orleans' slowly receding floodwaters was found Wednesday not to be overly polluted, encouraging news for a mayor weighing the reopening of the French Quarter and other dry parts of the city.

Mayor Ray Nagin had said a clean bill of health for the air would allow the tourist-friendly French Quarter and central business district to reopen as early as Monday. And while the Environmental Protection Agency still found the floodwaters contained dangerous levels of sewage-related bacteria, the air pollutants were determined to be at acceptable levels.

As the grim cleanup continued, Louisiana Gov. Kathleen Blanco took responsibility Wednesday for failures and missteps by the state government in the immediate aftermath of Hurricane Katrina. She pledged to remake New Orleans better than before the storm.

"To anyone who even suggests that this great city should not be rebuilt, hear this and hear it well: We will rebuild," she said, addressing a meeting of state lawmakers in Baton Rouge.

About 40 to 50 percent of the city was still flooded, down from 80 percent after Katrina hit, as 53 permanent and temporary pumps worked to siphon off 8 billion gallons a day.

On the hard-hit east side, block after block of once-flooded neighborhoods gave way to a slimy, putrid muck, ruined cars, snapped utility poles and collapsed houses.

Virtually all homes bore marks indicating they had been searched for victims. None in sight during a pass through neighborhoods had an additional numeral that would indicate bodies.

The body count in Louisiana alone climbed to 474 on Wednesday, and it was expected to rise further as state and federal officials went about the tedious task of collecting bodies and then using DNA to identify them.

"It's going to take months, maybe years," said Dr. Louis Cataldi, the coroner for Baton Rouge Parish. "This is not going away."

Coast Guard Vice Adm. Thad Allen, head of the federal hurricane response, outlined the procedures for body collection, including readings of ecumenical prayers and ceremonial washing of bodies in accordance with various religious traditions.

"This is a very, very sensitive process," Allen said. "We are mindful of the dignity that needs to be accorded to these remains."

The state attorney general's office said all of its investigators have been pulled from other tasks to work on the Medicaid Fraud Unit, the team whose work led to Tuesday's negligent homicide charges against the husband-and-wife owners of a Chalmette nursing home where 34 elderly residents drowned in floodwaters.