New York, NY —

With evidence of asbestos on the ground and buildings near the site of yesterday’s explosion, focus has shifted to possible dangers associated with cleaning it up.

REPORTER: Dr. Steven Levin, of Mt. Sinai Medical Center, says one of the main lessons of 9-11 is that cleanups – or at least testing – should be done by professionals, even when an affected area seems fairly small and harmless.

LEVIN: People were involved in cleaning up their own apartments. Some cleaned up their own offices. Some developed illness as a consequence, not from asbestos, but from other things in that dust. And here’s a situation where we don’t know what that dust contains unless someone’s going to do the testing.

REPORTER: Mayor Bloomberg has said no areas will be opened until the cleanup has been completed.