As many as 90 percent of fatalities in road accidents are caused by head injuries, highlighting the importance of helmets, a safety expert said Thursday.

A helmet might cost $10, but it is worth it, said Sann Socheata, manager of the road safety program for Handicap International Belgium.

"There should be thorough thinking, that is it $10 that can cure one's head if there is an injury by road accident," she said, as a guest on "Hello VOA."

Prime Minister Hun Sen on Monday urged motorcycle riders to wear a helmet, calling traffic deaths a worse tragedy than AIDS or land mines and reiterating a no-exception helmet law.

Sann Socheata said Thursday that riders who are ticketed by police, who often impose unofficial fines, should obtain a receipt.