Don't visit yet, slowly reviving New Orleans tells the tourists

The near-200,000 residents returning to some of New Orleans' neighbourhoods this week will face military checkpoints, little clean tap water, a dusk-to-dawn curfew and an ominous new health threat.

On Friday, tests of sediments across the city showed that diesel and fuel oils, which can take years to break down, comprise as much as a 10th of the weight of some sediment samples. City officials have installed tough security measures to ensure only residents with addresses in specified safe zones are allowed to return.

Health scares have already been raised over the presences of E coli, fecal bacteria and more than 100 chemicals in floodwaters. Scientists fear that, as the sediment dries, the pollutants in it will evaporate and turn to gases that people could inhale.

Fuel oils such as kerosene, jet fuel, range oil and home heating oil irritate the skin and, if breathed, cause nausea, headaches, increased blood pressure, lightheadedness, appetite loss, poor co-ordination and difficulty concen- trating. Breathing diesel fuel vapours for long periods can cause kidney damage and lower the blood's ability to clot.

Terry Ebbert, the mayor's homeland security director, said the repopulation of the city was being done "in a progressive manner" to ensure the safety and health of residents. "We're taking this in a stair-step approach," he said. "Until we feel comfortable about the security to allow people to reoccupy these areas, we will move forward very, very carefully."

Security will be tight in the reopened neighbourhoods, with Mayor Ray Nagin and others vowing never again to let New Orleans slip into the lawlessness that gripped the city in the days after the storm. He has warned potential looters that soldiers carry M-16 rifles "and they might have a few bazookas we're saving for special people". But the increased security is not entirely popular with residents, although it could prevent a premature revival of the previously booming tourist industry. Many residents say it will be weeks, if not months, before they are ready for late-night jazz, bawdy clubs and partying till dawn.

"We don't want a bunch of tourists in here while we're trying to get our homes together, get our businesses together" said Sandra Cimini, whose family owns a bar. "It's not going to be walking down the street with a hurricane glass in your hand until we can get everything together." Traffic is already heavy at checkpoints leading into Orleans Parish, where many were turned away if they had not managed to acquire the special business permits the city was issuing by fax in recent days.

The city planned to relax requirements over the weekend so anyone with documentation showing they had businesses in specified areas could enter. Those areas, for now, are Algiers, the French Quarter, the central business district and Uptown, which includes the Garden District.

As residents return, they also will be allowed in only if they can show a home address in a specified zone.

Forty per centof the city is still under water, and any rainfall of more than three inches could pose a further risk of extensive flooding. But the water level is dropping rapidly, from 20ft immediately after the hurricane to 5ft on Friday. As it drops the death toll rises. Yesterday it was 816 along the Gulf Coast, including 579 in Louisiana.

Despite the health risks, some business owners remained defiant. Franco Valobra, owner of a jewellery and antique shop in the French Quarter, called the curfew "ridiculous", adding: "There will be heavy traffic, there will be problems, but hey, we're over the hump. Once it's open, it's open."