By Tuesday afternoon, the smell had drastically improved and officials insist that even at its worst, the air was still safe to breathe. Still, at least one family, with a 2-week-old baby decided to stay in a hotel room Monday night, just in case.
People living near the ConocoPhillips pipeline in Concord say the smell from the leaking oil has been unbearable.
"It's pretty bad, nauseating. Your whole house smells because as soon as you turn on the heater, it sucks it in so everything smells," said Fred Hauntsman.
"We opened up our windows last night because we got calls from friends and it knocked us over. It smells like there's a refinery in our back yard," Kristin Wenger told ABC7.
ConocoPhillips officials say the leak in a 16-inch pipeline began Monday night, even thought residents say they had been smelling gas for days.
"I've been smelling it for like the last three or four days and today's the strongest. It's actually getting worse. It's like really bad now," Terrance O'Kelley said.
It got worse because when crews found it, they opened up the ground and truly let the smell out. Crews have since placed tarps and dirt over the crude oil to help rein in the odor.
"I know that there are odors and it's certainly inconvenient, to say the least," said Mark Hughes with ConocoPhillips. "We apologize for that and we're trying to remedy this as quickly as we can."
"It has to be wrong because you don't feel this way with clean air. You don't have a scratchy throat, light headed," Wenger said.
County officials say the air is safe and that the concentration of sulfur compounds would have to be about 1,000 times higher than it is to truly hurt someone. Still, this incident has left residents feeling nervous about the state of other pipelines and about the communication process.
"Where are the calls to the community? Because, we were all sitting around last night wondering, 'Do we leave? Do we stay?'" Wenger asked.
Hughes told ABC ConocoPhillips does not know what caused the leak or how much oil leaked out. They are working to drain all the oil out. Then, they will repair the pipe and hopefully get some more answers. It is unknown how long it will be before the smell completely goes away.