Most of the buildings closed because of a steam pipe explosion in Manhattan last week have been reopened, city officials said Saturday.

Of the 45 buildings tested for asbestos contamination, 39 have been cleared for people to return, officials said. Crews are still working to clean up the rest, they added.

The city Department of Environmental Protection also collected more than 1,800 outdoor air samples in the area to test for asbestos and determined that the air is safe for the public, officials said.

The cleanup is being done in response to the rupture of an aging Con Edison pipe containing cancer-causing asbestos. The blast on July 19 spewed a geyser of white vapor 10 stories high. It forced street closures and the evacuation of hundreds of people, but caused no major injuries.

Similar explosions over the year have drawn attention to the aging infrastructure beneath the streets of the nation’s largest city. Officials said the pipe that blew was installed in 1932.

More than 100 miles (161 kilometers) of steam pipe run beneath Manhattan, delivering vapor that powers heating and cooling systems, among other functions, in thousands of buildings. The pipes share the crowded underground with subway and commuter rail tunnels, telecommunications and electric cable, and water pipes.

(AP)