Nerval's Lobster writes "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. 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."