Would-be terrorists may have a harder time using a disastrous weapon on Washington D.C. now that DARPA (Defense Advanced Research Projects Agency) has tricked out some of the District’s EMS vehicles. The agency announced this week that for the past few months it’s been using73 radiation and nuclear detectors in the fleet of the city’s Fire and Emergency Medical Services ambulances to detect sources of radiation activity.

The SIGMA system is designed to scan the nation’s capital as efficiently as possible for any signs of a dirty bomb attack. So far, EMS vehicles have logged more than 100,000 hours of detector operation covering more than 150,000 miles, .

As for the detectors’ effectiveness, they can pick on on a wide range of radiation sources such as natural granite used in construction and lingering radiation after certain medical treatments. The SIGMA system can distinguish the difference between these harmless detections and actually threats. Another key feature of the system is its mapping of areas in the city that can be used in the future to distinguish radiation patterns over periods of time.

Here is a little blurb on how they work:

DARPA’s SIGMA system has developed two types of radiation detectors—a larger size like those recently deployed in the emergency vehicle tests and inexpensive, smartphone-sized mobile devices that can be worn on a belt by police officers or others. The devices run on advanced software that can detect the tiniest traces of radioactive materials. Those devices, networked with detectors along major roadways, bridges, and other fixed infrastructure, promise significantly enhanced awareness of radiation sources and greater advance warning of possible threats. The SIGMA detectors themselves do not emit radiation but detect gamma and neutron radiation emanating from sources.

DARPA hopes to deploy the SIGMA system to other major cities in the U.S. beyond just EMS vehicles, though the agency’s statement didn’t mention what it has in mind.

Indeed, the threat of domestic terrorists carrying out a dirty bomb attack is very real. reported last year on how easy it is for people to get radioactive material. The Government Accountability Office pretended to be a clandestine group of fewer than 10 people with a fake company that wanted to conduct gas and oil exploration. The GAO group easily secured a license from Texas regulators, who were deputized by Nuclear Regulatory Commission (NRC).

Getting the license locally helped the GAO shell company avoid federal oversight and allowed them to procure radioactive materials easier, per the Center’s reporting:

Here’s how they did it: In Dallas, they incorporated a shell company they never intended to run and rented office space in a nondescript industrial park, merely to create an address for the license application. In a spot on the form where they were supposed to identify their safety officer, they made up a name and attached a fake résumé. They claimed to need the material to power an industrial gauge used in oil and gas exploration.

Last year, their application was sent not to Washington but to Texas regulators, who had been deputized by the NRC to grant licenses without federal review. When the state’s inspector visited the fake office, he saw it was empty and had no security precautions. But members of the group assured him that once they had a license, they would be able to make the security and safety improvements.

So the inspector, who always carried licenses with him, handed them one on the spot.

The two-page Texas document authorized the company to buy the sealed radioactive material in an amount smaller than needed for any nefarious purpose. But no copies were required to be kept in a readily-accessible, government database. So after using the license to place one order, the team simply made a digital copy and changed the permitted quantities, enabling it to place a new order with another seller for twice the original amount.

“I wouldn’t call what we did very sophisticated,” Ned Woodward, the mastermind of the Government Accountability Office’s plot, said in a phone interview with . “There was nothing we had done to improve that site to make it appear as if it were an ongoing business.”

If that sounds frightening to you, it should. In this case, deregulation allowed a group of people—thankfully, the feds checking their own security—to obtain radioactive material. Just imagine how easy it could have been to get those materials to the streets.

DARPA’s efforts to outfit EMTs to patrol for radiation is a smart one. Perhaps with the exception of police cars, there is no city government vehicle that combs as much municipal territory than EMTs. So far, the program seems to be working in Washington D.C., increasing the likelihood of the system going nationwide.