The mercury was first discovered near a garbage can outside of the town's Amtrak station Monday.
Then on Tuesday, health officials said they found traces of mercury on several roads surrounding the train station after a truck picked up the leaking trash can.
And on Wednesday, more traces were found along another road leading up to Rankin Park.
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"Maybe I need to get rid of the shoes, have them tested? What do I do?" said Abel Vanegas.
Contra Costa Public Health has stressed that the mercury levels found outside are an extremely low risk to people's health.
They also say that while small levels of mercury were found on the road, the sidewalks in the area are safe to walk on.
Their main worry was those who might have stepped in the initial puddle near the Amtrak station Monday and then tracked it into their homes.
Once inside, high levels of mercury can create more serious risks.
"I do have concern about Martinez and our health, and what is being done to protect us from horrible contamination," said resident Stephanie Telfer.
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Telfer runs a local kids camp in town and says several people she works with have worries.
"I actually had some parents call me and were concerned that our road would be closed to camp," she said. "And they were also really concerned about contamination."
The streets of downtown Martinez were quiet Wednesday night as some residents told ABC7 News they're avoiding the area until the mercury is cleaned up.
Karissa Gerhke says since she moved to town a couple of years ago, her family has experienced two health hazards.
First the Martinez refinery's unexpected release of ash into the air last Thanksgiving, and now the mercury.
"Now I'm worried that we can't walk our child through near the Amtrak to go to the park," Gerhke said.
As of Wednesday night, police are still investigating where the mercury came from.