NORFOLK, Va. (AP) — The U.S. Navy is banning vaping on ships after at least a dozen reports of explosions and injuries.

Naval commanders said in a statement Friday that the temporary electronic cigarette policy aims to protect sailors and the fleet. It starts next month.

Officials cited overheated batteries in vaping equipment as the problem. Explosions have led to fires, first-degree burns and facial disfigurement. During a recent eight-month stretch, 12 incidents put sailors out of work for a combined 77 days. Injuries also restricted some to light duty for a total of five months.

The policy goes into effect May 14, but sailors at sea can request extensions. The Navy says it will make a final determination on e-cigarettes after more analysis.

Vaping will still be allowed on land in designated areas.