John O'Neill remembers the white dust coating everything.

And Elsie Goss-Caldwell remembers the sickening smell of smoke the next day.

An emergency manager. A firefighter. A mother.

Their lives were scarred by 9/11. And at this time of year, the only thing worse than remembering the events of that cruel Tuesday six years ago - is forgetting them.

"I like the fact that I knew precise times. The first plane hit at 8:46 a.m. The second plane hit at 9:06. . . . I used to be able to rattle off those times very quickly, and now I can't remember any of that," said Marrocolo, Philadelphia's top emergency planner, who had been working for New York City's emergency office.

For Marrocolo and others, the anniversary of 9/11 is a time to remember and to remind others of the horror of that day.

"What concerns me is that I think people are starting to forget how horrible 9/11 was," Marrocolo said, ". . . and if I can't remember these precise details, I feel like my ability to explain the event becomes more difficult."

And so, she and others turn back the clock to 8:46.40 a.m. on Sept. 11, 2001.

MaryAnn Marrocolo, former emergency planner for New York City, who worked on the 23d floor of Seven World Trade Center.

"I was going through the Brooklyn-Battery Tunnel, and I had just come out of the tunnel on the Manhattan side when someone from my office called me and said a plane had just hit the World Trade Center. . . . At first I didn't believe him.

"I wasn't going to be able to get through all the traffic, so I walked from the tunnel to the trade center . . . and I ran through the plaza area to Seven World Trade Center.

"A lot of smoke and debris was falling from above. A couple of times, I looked up, and you could clearly see people standing at the edges of where the windows were broken, or they were actually falling through the sky. I saw maybe five or six people who were in the process of falling."

Marrocolo was inside the city's Emergency Operations Center (EOC) on the 23d floor when the second plane hit.

"There weren't any windows. We saw it on TV and you felt the building shake. . . . That's when we realized that this wasn't just a freak accident, that this was some orchestrated attack.

"We went down the stairs - 23 flights - and then we ended up in the lobby of Seven World Trade Center. . . . Outside, there was glass falling and things hitting the ground."

Marrocolo was helping to set up a triage area in the lobby and telling city personnel who were arriving on the scene where the emergency operations center had moved when the South Tower collapsed.

"The glass in the lobby was breaking, and it was clear something bad was going to happen. . . . We were trapped very briefly, and we couldn't figure how to get out of the building, because a lot of the entrances were blocked and the lobby had been completely destroyed.

"When the dust cleared a little bit, it was amazingly quiet . . . and then the sound most disturbing was, you could hear the firefighters' pass devices, the accountability devices. When a firefighter doesn't move for a period of 30 to 60 seconds, this device goes off. It's a loud beeping noise, and I remember you could hear a lot of that. It was very eerie, because that means they're not moving."