NEW YORK (WABC) -- The MTA says the foul stench people are smelling in L train subway stations is not toxic, but the transit union isn't so sure.
Officials say three workers were taken to the hospital after getting sick.
The smell was still present at the Graham and Metropolitan L train station in Williamsburg Thursday, after ambulances were called Wednesday when workers reported feeling nauseous and lightheaded.
"It just smells like burning rubber," commuter Nissa Shabazz said.
Two workers were taken to the hospital Wednesday, and at least one was taken Tuesday.
The MTA says they are using fans dissipate the smell and are also using pads to soak up the oil sheen that they say was seeping up from the ground.
"It's been about a week, it smells like gas a couple stops," rider Eloise Danch said.
What is behind the smell is really unclear. The MTA said earlier they believed it was heating oil, but MTA Chief Safety Officer Pat Warren said Wednesday that they don't know what the substance is that is causing the smell.
Still, they are reassuring riders and workers that it is safe.
"It is not toxic in any way," Warren said. "It may be obnoxious to people to smell the fumes or the odor down there, but it is not in any way toxic or unsafe."
The Transit Workers Union wants to know how the MTA can assure people they're safe if they don't know what the substance is.
"I don't believe half of what people say," Shabazz said. "You know, most of the time, it's to keep calm, keep everybody from panicking."
Environmental officials have taken samples of the substance to test it.
In the meantime, MTA has been handing out masks to its employees.
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L train station smell sickens at least 3 MTA workers in Brooklyn