New Yorkers are still questioning their air's safety after a steam pipe eruption spewed dirt and debris into the sky over midtown. Many remember the cover-up after the last major pipe rupture and the illnesses ground zero workers faced years after officials assured them lower Manhattan was safe.

Mayor Michael Bloomberg on Thursday declared the air free of asbestos, saying "every single test" showed no asbestos in the air. Other city officials were unwavering in that assessment, as well.

Yet, the painful legacy of the Sept. 11, 2001, terrorist attacks was evident among area residents and workers.

The debris from Wednesday's rupture was nothing close to the scale of the twin towers' collapse, but the sight of police in filtration masks and the warnings to area residents to keep windows closed and to throw out any clothing touched by dust or debris added to people's fears.

• PHOTO ESSAY: Steam Pipe Explodes in Midtown Manhattan

"I take everything with a grain of salt. I would like to believe it, but I can't," said Ariana Reines, an English teacher who returned to her school on a block of Lexington Avenue that was closed off after Wednesday evening's rupture.

Many of the city's older steam pipes are lined with asbestos, a carcinogen that can cause serious illnesses with longterm exposure. The dust and debris churned up when the 83-year-old pipe burst showed some signs of asbestos on the ground; officials said 14 of 56 debris samples tested positive, though most had only trace amounts.

A deadly 1989 rupture of another steam pipe near Manhattan's Gramercy Park also spewed asbestos — a fact utility Con Ed later admitted it had concealed for days while residents were exposed.

Andrew Troisi, spokesman for the Office of Emergency Management, said the city agency encouraged people to stay away from the area of Wednesday's blast as a precaution and that it believed long-term health problems from the rupture were "unlikely."

"All indications are that there are no airborne contaminants, and furthermore, exposure to asbestos over a short period of time is not dangerous," he said.

Police officers wore respiration masks in the "frozen zone" — a three-square-block area around the explosion crater that was closed to traffic and pedestrians. Most passers-by, though, had nothing to filter the air.

"I don't know anybody here who's going out to lunch," said attorney Jordan Fox, who was working a block from the rupture site and has been involved in asbestos cases. "It's musty out there — it's humid, and the air is kind of thick. That could keep the asbestos entrained in the air."

"They lied to us on Sept. 11 and thereafter. It's clear they misrepresented exposure after 9/11," Fox said. "A lot of people would ask, 'Why should we trust them now?"'

• PHOTO ESSAY: Steam Pipe Explodes in Midtown Manhattan