Mr. James DeCouto is to spend seven days and seven nights on top of an advertising hoarding in the middle of Jackson, Tennessee.

And Mr. DeCouto will only be allowed down from his four foot by six foot perch for an hour each day to use the bathroom.

His marathon effort is also set to receive worldwide coverage, beginning with an appearance on ABC-TV's "Good Morning America.'' Former Saltus student, Mr. DeCouto, 28, has worked for the group Habitat for Humanity in Jackson for the past three years.

"Habitat is an organisation that builds homes for low income families,'' he explained yesterday.

"It opened its Jackson office in 1986 and aims to eliminate poverty housing in Jackson. But it has built many houses across the United States, Mexico and Guatemala.'' Habitat is backed by former US President Jimmy Carter who recently launched a campaign to build 30 houses in a week in the southern US states.

Mr. DeCouto said his charity event was a new form of advertising for the organisation. He would have a "thermometer'' to show how much money had been raised and different forms of Habitat advertising, including the slogan "No More Shacks.'' "It is estimated that 200,000 people pass the billboard every day and if half of them stop and think about this then it will be good,'' he added.

"We are hoping it will encourage people to give money to Habitat. We are hoping to raise $50,000 -- enough to build two new homes.'' He starts his marathon on April 10 and is expecting to appear on "Good Morning America'' the following day.

He said: "I will be allowed down for an hour a day for a shower and the basic necessities.

"The top of the board is just large enough to stop me rolling off when I am asleep.'' Mr. DeCouto decided to get involved with Habitat after noticing the advertising booklet which describes how people struggle against the odds to make their poverty housing presentable.

He moved from Bermuda with his parents Mr. Gerry and Mrs. Mary DeCouto to Florida. He studied in the US before finding work with Habitat.