Old metal gas pipes pose deadly leak dangers across the US—yet we still have tens of thousands of miles of them under our feet, USA Today reports. The threat may seem small, but in fact, blasts from leaks have hurt or killed people or damaged property approximately every two days for the past 10 years, the newspaper finds in an investigation. The toll from the worst cases: 135 lives, 600 injuries, and $2 billion in damages. The primary problem is with cast-iron and bare-steel gas pipes, some of which date back a century or more. Officials are well aware of the problem, and though thousands of miles of the pipes have been replaced, some 85,000 miles remain.
The biggest danger is in cities, where it's tougher and pricier to replace old piping among the busy streets—the cost is typically several million dollars per mile, versus $1 million elsewhere. New York, Boston, and Detroit host a third of the questionable iron pipes. "The chance of a pipeline failing in any one place is pretty small, but if you live in one of those older East Coast cities with hundreds of miles of cast-iron pipe, that's just a failure waiting to happen," says a safety advocate. But smaller cities like Pensacola, Fla., are at risk too, USA Today notes. Replacement efforts are under way, but they could take decades and so far haven't been required by the US government. Click for the full investigation.