At 5 a.m. when Pamela Vasquez would arrive at the Citgo gas station in Fields Corner where she works, it was no surprise to see a line of people there, anxiously waiting.

But they weren’t looking to fuel up their cars or buy snacks or scratch-offs from the Quick Mart.

Instead, they were there to purchase what is called synthetic marijuana, also known as K2, spice, crazy monkey, and Scooby snacks, a designer drug that does not actually contain marijuana but is made-up of a variety of plants sprayed with chemicals, according to Boston police and the Centers for Disease Control. It is often marketed as incense or potpourri.

The popular drugs, which can cause hallucinations and psychotic episodes, are legal — raising the concerns of Boston police, who are working with City Council to ban the substances.

Under a proposal sponsored by City Councilor Frank Baker, any person selling synthetic marijuana could be fined $300 for each day they continue to sell the products. A person in possession of the drugs would also be fined $300. The proposal is slated for a hearing Wednesday in City Hall.