(Bloomberg) – A Washington-based auto safety group is repeating its call for Ford Motor Co. to recall more than a million Explorer sport-utility vehicles, citing an increase in the number of complaints about exhaust fumes seeping inside the vehicles.

Nearly 1,400 complaints about the exhaust fumes in the sport utility vehicles have been lodged with regulators, according to a tally by the the Center for Auto Safety. Hundreds of people said they had been affected by fumes, and the complaints included reports of more than 80 injuries. 

Internal investigation

The automaker in October announced a nationwide service campaign to reduce the potential for exhaust fumes to enter the cabins and said that an internal investigation had not found carbon monoxide levels exceeding what people are exposed to every day.

"Explorers are safe," Ford said in a statement Tuesday, adding that concerned customers can visit their dealer for a free repair. "Ford's investigation and extensive testing has not found carbon monoxide levels that exceed what people are exposed to every day."

Carbon monoxide exposure

According to the complaints, drivers reported feeling ill, with symptoms ranging from headaches and dizziness to nausea and loss of consciousness, Jason Levine, executive director of the Center for Auto Safety, said in a statement on Tuesday. No deaths have been reported.