The Montgomery County Planning Board has turned down a request by Costco to open a 16-pump gas station as part of its new warehouse store at the Westfield Wheaton Mall.

The board voted 3-2 Thursday night to recommend denial, citing potential health risks posed by long queues of automobiles close to residential areas. Members also said a retail gas business did not fit into long-term plans to reduce automobile use in the area around the Wheaton Metro station.

The gas station proposal has been fought by civic activists in Kensington for nearly three years. The Montgomery County Council unanimously voted last July to bar large stations within 300 feet of schools or recreation facilities, a measure specifically aimed at Costco. The company lobbied intensively against the law, which originally called for a 1,000 foot buffer.

After the council’s action, the company submitted a new proposal, moving the gas station site 300 feet to the east.

The board will send its recommendation to a hearing examiner and a final decision by the county Board of Appeals. The Costco store is scheduled to open next month.