Officials from Philadelphia Emergency Management confirmed the smell came from the Sunoco refinery on Passyunk Avenue.
The refinery was emptying a tank, and something spilled on its floating roof.
Sunoco said the material does not pose a health hazard, but created the foul smell that can be described as sulfur.
Tests from the NJ DEP also indicate this is nontoxic.
Sunoco said it is working to clean up the problem.
