According to the engineers, the design for the Vista tower "would result in building occupants feeling ill and possibly afraid for their safety," Chicago's zoning administrator, Patricia Scudiero, wrote in an April 26 letter to Jack George, a lawyer for project's developers.To prevent that, the developers requested — and the city OKed — an unusual change to the already-approved plan for the building: The 83rd floor of the 98-story, 1,198-foot East Wacker Drive tower will be an empty space that Chicago's famous winds can blow through. If