The landscape of Manhattan will forever be changed following the attacks of September 11th. People who once felt secure living and working on the island are now apprehensive about the future.

One Irish man I spoke to said he felt an uneasiness about coming into the city to work each morning; for extra security he carries a gas mask in his bag for his subway ride from Queens to midtown.

Until April, I spent four years working in an office downtown. I used to catch a PATH train from Hoboken, New Jersey, under the Hudson River to the World Trade Centre, and from there I walked a few blocks south.

My office was on the 26th floor of a high-rise building and I never worried about its location because it offered beautiful views of Ellis Island and the Statue of Liberty.

Now, I can hardly recognise the area because of the destruction and devastation caused. About 15 million square feet of office space has been destroyed.

That is less than half of 1 per cent of the office space in the country, but the cost of clearing the rubble and rebuilding will run into billions of dollars.

Since the attacks, of course, people's nerves are more frayed. I have heard that some employees of a major investment bank working in a skyscraper near Wall Street have been calling in sick or working from home, while many are looking for new jobs outside the city. Wall Street's proximity to the World Trade Centre and the possible dangers of working in a skyscraper have taken their toll.

An IT systems professional in New Jersey, whose job had been downsized, told me he had been called back to work. His company needs people to help recover computer systems that were damaged in the explosions. These computers were stored in the upper offices of a small building owned by a financial institution in the vicinity of the World Trade Centre. Like other companies, their back-up servers are housed across the Hudson River in New Jersey.

Even though he knows the IT market is looking shaky, he says the parameters of his job search have changed.

"When looking at many job search websites, you can specify your preferred working location," he said.

"As soon as these attacks happened, I took New York off my list and I wouldn't be surprised if many other people did likewise."

He now says he would like to work closer to home in suburban New Jersey or Connecticut.

Although technical jobs in Manhattan still pay better than elsewhere, "I would have a certain amount of wariness about accepting an assignment in Manhattan. I'd rather take the risk and commute to Connecticut," he says.

There are also the logistics of getting into work in downtown Manhattan these days. Some of the subway lines have been destroyed and will take years to rebuild. There is no direct route to Wall Street from New Jersey. Some of the trains only run to midtown and the ferries operate to certain locations.

"If there was another incident, would you really want to be stuck on an island you couldn't get off?" this man asked.

The Star Ledger, a major newspaper in northern New Jersey, stated this week that New Jersey Transit may have to put off the scheduled opening of a $450 million (€491 million) rail transfer station in Secaucus (to transfer train commuters from all parts of New Jersey to Manhattan) because capacity on the midtown Manhattan train evaporated overnight.

Another IT employee, who wished to remain anonymous, said: "Many corporations will look at the experience of companies like Cantor Fitzgerald, which lost more than 730 of its 1,000 employees who worked in the World Trade Centre's north tower."

Some companies, which are headquartered in Manhattan, are considering relocating their commercial offices to Westchester County in upstate New York, Connecticut or New Jersey.

"They are re-evaluating having all or most of their employees at the same location," he said. "Many companies may retain a symbolic presence in New York City but move other operations, especially mission-critical IT applications, to nondescript office complexes in the suburbs."

This idea of satellite offices is taking hold.

One friend who works for a New Jersey development company said her office has been fielding calls from companies desperate to find rental space in the New Jersey Meadowlands area, about seven miles from Manhattan, until they can decide what to do in the long-term.

Even some of the usual red tape required in such transactions is being waived. The same holds true for residential real estate. Some buildings in Manhattan that had been slated for apartment blocks are now being converted into office space and people who had been living in places like Battery Park City, near the wreckage of the World Trade Centre, are now thinking about leaving the city for life in the suburbs.

The air is still smoky down there and phone lines in some buildings are still down. Employees have had to buy mobile phones in order to carry out day-to-day business. One friend who works in the area told me that I was lucky to have left there when I did. Others, unfortunately, didn't have the chance to do so.