At least 15 people were treated for exposure to ammonia Monday after a major leak at Pier 38.
One person was transported to a hospital, while the rest were treated on scene and refused further service.
More than 100 people were evacuated from businesses and fishing vessels in the area after the chemical leak was reported about 5:14 p.m.
On Tuesday morning, most businesses were allowed to re-open except for the Hawaiian Ice Company.
Fire Capt. David Jenkins said there's "potential" that a 6,500-pound container at Hawaiian Ice Company may have been involved, but he said the cause is still under investigation.
Ammonia can be used as a refrigerant, but is highly irritating to the eyes and respiratory tract.
Some 43 firefighters responded to the scene, clearing out employees and customers and restricting access to affected sites. Late Monday, hazardous material crews were taking meter readings to determine how high the levels of ammonia remained in the area.
Nico's employee Jared Shiraishi said it "smelled like hair dye" after the spill was reported.
"All of a sudden I got lightheaded and I couldn't breathe," he said.
Employees also described a chaotic scene as the strong smells of ammonia caused some to pass out or feel faint in eateries near Hawaiian Ice.
Said Nico's employee Maile Wong, "I'm sure some of them (the customers) were scared because they didn't know what was going on."
Firefighters were still on scene early Tuesday ventilating the building and taking meter readings.