[caption id="attachment_13657" align="aligncenter" width="300"] It's a smelly job, but somebody's got to do it.[/caption] Talk about the Internet of Things (in unsavory places): The National Security Agency may never wean itself from its digital-data habit, but security agencies in Europe have found a whole new way to identify and approach bombmakers and other potentially dangerous radicals. The only problem with the approach is that it stinks. Literally. Researchers in a European-Union funded project called Emphasis are developing chemical sensors that can be embedded in networks of underground sewage tunnels to sniff the air and phone home at the first hint of chemical residue from the manufacture of bombs. Using remote sensors might be effective because the liquid- and gas byproducts of bomb production – and manufacture of many drugs as well – leak, seep or are poured into sinks and toilets to get rid of the evidence, according to Hans Onnerud, an analytical chemist with the Swedish Defense Research Agency. Other gases and residue remain airborne, but escape the buildings where bomb- or drug-makers are working; those also often make it into the sewers, according to an article published in New Scientist Oct. 31. With such a catchall underneath the city streets, and the chemical wherewithal to identify which smells belong to bombs or drugs and which belong to other things, it should be possible to keep a close watch on development of dangerous materials in a city without invading the homes of residents, Onnerud added. In fact, if sewer-sniffing technology had been in place in 2005, British authorities might have had a much easier time tracing the location of the bombers, or even detecting them ahead of time and stopping the London subway bomb attack that killed 54 people. Fumes from the bombs used in those attacks, which were assembled in a house in Leeds that had been turned into a compact bomb factory, were strong enough to kill plants in the garden. It's extremely likely they would have been detectable from the sewer as well, Onnerud said in a statement announcing Emphasis. The sensors developed for Emphasis are designed to detect chemical reagents produced by the breakdown of chemicals in bombs. Each sensor is a 10-centimeter-long electrode that can be submersed in sewer wastewater to look for ions of the right configuration. As anyone who has ever seen a Batman movie can testify, simply identifying trouble in the sewer isn't enough to save the day. Emphasis sensors are there simply to give warning if they detect anything. If they do, they'll raise an alarm by sending a message to police headquarters, which will dispatch officers with more sensitive chemical sniffers to pinpoint the place in the sewers from which the explosives came. Aboveground, they would use infrared lasers to find the spectra of vapor molecules that outgas from the explosives. While leaning heavily on sewer-chemical theories and assuming access to the underground that is never as easy as it sounds, the approach has been proven to work. In 2011, researchers at the University of Adelaide, Australia found they could not only detect indicators of illicit drugs in the city's sewer waters, they could do it accurately enough, and predict drug use of citizens consistently enough, to be able to tell the day of the week by the volume of illicit drugs in the sewers. Using data from the sewers, the two researchers were able to determine that use of the rave drug ecstasy in Adelaide is five times higher during the weekend than during the week, for example. "Placing sensors in the sewer system may be a cheap and quick way to monitor illicit drugs, particularly by-products of their production which will be present in much higher concentrations than metabolites from users," according to Chang Chen, one of the two researchers on the project. Leaving sensors in the filthiest environment attached to any city may not be a reliable long-term way to monitor dangers like bomb-making, whoever, according to Rachel Cunningham, spokesperson for Thames Water, which manages London sewers. The volume of much, trash, prescription medicines and waste products is so high it could easily smother sensors left down there for any length of time, she said. Image: New Scientist/Dan Salisbury