Earlier in the day, officials from Philadelphia Energy Solutions said it appeared the smell came from a cleaning operation at the company's former plant in South Philadelphia.
The suspicion was that the cleaning released the chemical mercaptan, which is used to give natural gas a foul smell.
However, by mid-afternoon, the Office of Emergency Management said an investigation by the Philadelphia Fire Department could not verify the mercaptan release.
"Despite some initial reports that perhaps some cleaning work they were doing on a tank down there was the source of the odor. We actually went in and checked that vessel or hazmat taskforce did, and did not find that to be the source of the odors," said Philadelphia Fire Commissioner Adam Thiel.
According to Theil, the PES Refinery did have a reading on their fenceline monitoring system that suggests some type of product went across their facility, from an unknown location around 7:30 to 8 a.m.
"We've checked with New Jersey DEP, obviously there are other refineries and industrial facilities in the region, and there are no reported releases from any of those facilities. So, frankly, at this point, we don't know what the cause of these odor is," said Theil.
The Philadelphia Fire Department will continue to investigate any reports of unusual odors.
Thiel says more than 500 emergency calls were made related to the odor, but the source still remains undetermined.
"We have not found any hazardous conditions on the incidents that we investigated," Theil said.
If you smell gasoline or you smell anything, do not hesitate to call 911.
The former refinery was the scene of a large explosion last summer.