Voters will go to the polls in a special election July 19 to decide whether to uphold a leaf-blower ban approved by Town Meeting in May. The polls will be open from 2 to 8 p.m. Town Meeting members voted, 95 to 85, to ban gas-powered leaf blowers on private property between May 15 and Oct. 15, based on concerns about noise and potentially harmful debris kicked up by the machines. A group of landscapers and residents gathered enough petition signatures to call the special election, which is expected to cost the town about $30,000. A majority vote against the new rule must include at least 20 percent of Arlington’s registered voters for Town Meeting’s decision to be overturned.