Building owners in major cities around the nation are suspending use of revolving doors and checking them for safety following the death last week of a 6-year-old boy at the Roppongi Hills complex in Tokyo and revelations that 32 similar accidents have taken place at the site since it opened last April.

While the police investigation has focused on the Roppongi door's sensor system, the accident has also raised the question of why these potentially hazardous doors have become so popular.

According to Tokyo Metropolitan Government officials, there are at least 260 automatic revolving doors in Tokyo, most of which are less than three years old and are installed at hotels and high-rise office buildings.