Dennis Smith, retired New York City firefighter and best-selling author of "Report from Ground Zero," volunteered to help in the rescue efforts minutes after the second tower fell Sept. 11, 2001.

For the next 50 days, he sifted through rubble, searching for friends and former colleagues buried beneath the 70-foot mounds of rubble.

He spoke Tuesday at the New York State Writers Institute about his experiences, discussing the first minutes on the scene, questioning the construction of the towers and honoring the firefighters who were lost. About 35 people attended the afternoon seminar.

Smith said he vividly remembers many images from Sept. 11, but he has completely forgotten blocks of hours from the day.

"The air was oatmeal-thick. It was very quiet. The emergency vehicles could not get within seven blocks."

"When we got to the site it was an eerie sort of silence and oatmeallike air. It was utterly colorless; everything was gray."

Occasionally, Smith said, one could see the red from fires; 100 cars were on fire.

At first, his only concern was to try to rescue people buried in the rubble.

"I would ask you to remember, I had many friends who were buried. My fundamental obligation was to rescue them," he said.

Eventually, several days after the attacks, he agreed to write an op-ed piece for the New York Times. The day after it appeared, seven publishing companies contacted him.

He said he was compelled to write a book about it for several reasons. "I knew, in a book, I would be able to be put in front of the book the names of the 343 firefighters, 23 [city] police officers and 37 Port Authority officers. As long as a Library of Congress existed, these names would be in a book, all 403 of them, and they would be preserved.

"I never felt this book was about me, but about the people who gave more than anyone had a right to ask them to give."

Smith said he wanted to get the history right _ he knew the story was too big for any one person to tell accurately.

He didn't want the book to be subject to second-guessing in the future, so he recorded his own observations and interviewed other rescue workers.

This, he felt, would ensure the book would provide a credible account that would stand the test of time. He also said if he was going to write a book, he wanted to set a standard for charitable giving. He gives a percentage of the royalties from the book to the Foundation for American Firefighters, which provides money to the New York Police & Fire Widows and Children Benefits Fund.

It's difficult to get a sense of how gigantic the World Trade Center site was, he said. Nine city square blocks were reduced to 16 acres of rubble, a series of mounds 60 and 70 feet high. "To wonder where anyone might be was the most amazing thing," he said.

Smith began his career in the Fire Department of New York and served in the South Bronx. He has written several books about firefighting and a memoir.

As an 18-year department veteran, he said he has a lot of questions in his own mind about the day, including problems with the design of the buildings. During his hourlong talk Tuesday at the University at Albany campus, he discussed the fundamental design flaw of the World Trade Center, which he likened to the Titanic in its magnitude.

He compared the building to a huge straw with a steel rod down the center - in the middle were 99 elevators and three stairwells. The rest was open space.

It was the first such building in New York, and its design increased rentable space 25 percent. But Smith said no one had ever studied what might happen if there was a comprehensive fire in the World Trade Center, and no evidence exists that anyone studied how to respond.

New York City codes require that steel girders must be able to withstand four hours of fire before the steel begins to melt.

The fire chiefs and other officials believed they had two hours before the steel would melt _ 50 percent of the four-hour requirement.

They never anticipated the buildings would fall so quickly, Smith said.